You need to look at hypothetical situations to begin to understand what is happening here. For example, if there are no rules, she won't be able to break them. OK, that is extreme. But if you want to teach her to follow rules, the first thing you do (think - with a baby) is set rules the baby is already doing.
Next - put in rules the baby can follow, can understand and can learn. For example, you don't ask a baby to do trigonometry in order to earn the right to have a glass of juice. With your daughter, it seems to me you are asking her to comply with rules she cannot comply with, or cannot understand.
When I say "cannot comply with" I don't mean she is physically unable to comply with, but in her case the compulsion to do whatever it is is just too strong.
An example from a niece of mine - she was about two years old, we were at a family barbecue at her aunt's place (another of my sister's). I watched this little girl take a clod of earth from the garden, walk to the path and drop it and watch it break. She would go back, get another clod of earth and take it to the path and drop it, watching. It was fascinating to me - this two-year-old was clearly, to me, studying the way the clods of earth broke up on impact.
Her mother called her for lunch.
The little girl ignored her. I'm fairly sure she heard (or I was sure at the time - not so sure now) and my other sister (the one whose house it was) said, "Oh, she's being deliberately naughty, she's disobeying you on purpose."
I said, "I think she's made a decision in her own mind that what she is doing now, is more important than doing what she has been told."
Our hostess said angrily, "She's only two! Stop trying to analyse everyone and everything! She's just being a naughty girl!"
But I don't think she was old enough to fully understand "naughty". She was doing something of incredible fascination to her and the most important thing to her right then, was to finish it. If we tried to impose rules on her right then, it was guaranteed that she would ignore them.
What happened - her mother came and fetched her (did not smack her, as our sister said she should). My niece screamed in outrage at being interrupted, but smacking would have escalated this. So she did eat some lunch, but kept wanting to get down to go back to the garden. She did eat her lunch then went back to dropping clods of earth. When she had finished, I got the broom and made sure my little niece watched while I swept the dirt back onto the garden. Not a punishment - just a job that her game had produced.
In a lot of ways, kids like ours are still at that 2 year old level. They get caught up in "I MUST do this, and do it now," and any other rule can never take precedence.
Now, if your child is continually breaking the rules, then you are losing face and she is learning that rules can get broken after all. Of course you then get angry, so she learns the next stage - people get angry.
The connection between "I broke the rules - people get angry" doesn't happen. And that is the connection you need, in order for rules to be learned. The more the rules get broken, the harder it is to learn to obey those rules (especially if she's Aspie). You can build up negative correlations just as fast as positive ones, and any habits take a lot longer to be unlearned.
Some rules you have may not be needed. And some rules may be needed but may be able to be learned a different way. She is very young for this, however. Still, the more obvious rules may be able to be learned by using "natural consequences". You could, for example, let her eat the snacks she wants but tell her she needs to be sure she can still eat her dinner; and then when she can't eat her dinner, gently remind her that she misjudged her hunger.
Or what I used to do - at 5, kids get hungry but also get tired. I made sure I had a fridge full of healthy food, the sort they could eat as snacks or as a meal. My kids would come home to a fridge stocked with carrot sticks, celery sticks, cheese slices and cold cooked sausages. They knew fairly quickly what they were permitted to help themselves to. If they wanted "comfort food" such as noodles or cake, they had to eat enough healthy food first, to satisfy me. I wouldn't make them eat something they didn't like, but we had to work to find what they DID like that was on my 'healthy' list. We found some surprising foods that the kids liked.
They would, at 5, come home from school absolutely ravenous. Sometimes they hadn't eaten their lunch (we "brown bag" it in Australia) and if it was still edible, I would make them eat it then. And/or I would let them have a sausage or piece of chicken and some salad vegetables. If I had leftover roast chicken and leftover roast vegetables, I might microwave a small plate of fresh roast dinner.
Often, when they were 5, they would come home, eat a lot, then get sleepy. It had been a long day at school so we often put the kids to bed earlier than before they had started school, and know they had just had a healthy meal.
If the child ate a full (but early) dinner (as a series of snacks) they could still eat more at the dinner table, but I would serve a lot less so they didn't feel too overloaded with food. The rule is, "Take all you want, but eat all you take."
I know this sounds anarchic, but from a parenting point of view, it solved a lot of problems - the child ate when the child was hungry. The child ate, over the day, balanced, healthy meals. The child learned to enjoy healthy food and to not over-eat or over-indulge (with the exception of easy child, whose problems in this area puzzle me but I think have a physiological cause). The child was not trying to eat when too tired because the day's efforts have caught up with him/her. We got to eat our meal with tranquility.
As the child got more accustomed to school routine and the efforts involved, the child was more able to wait and eat a full meal with the family.
Another thing - we raised a family of faddy eaters. Or to be more precise - they were faddy despite our approach, not because of it. easy child & difficult child 1 were fine, no fads/phobias. But easy child 2/FDF2 would only eat creamy textures, and no "bits" in anything. No food allowed to touch. While difficult child 3 would NOT eat anything creamy, preferred his food to be chunky and mixed together. it was Jack Spratt and his wife... and in the interests of both harmony, andensuring that the kids didn't starve, I catered to it to a certain extent. Modern conveniences make this a fairly easy task.
Now, I know they say that kids won't self-starve past a certain point, but that is NORMAL kids. When you have a kid who is already so underweight that doctors and government nurse practitioners look askance at you, you do your utmost to get your kid to eat. My three younger kids (especially the youngest two) were always underweight. So I found foods they liked and cooked those foods in bulk.
The kids like noodles - so I learned how to make my own egg noodles, really quickly. I found methods which worked well for me. Having so much egg in the noodle meant the kids were getting a high protein meal.
I'm not saying you should do this, only the reasoning behind the way I did things.
basically what I did - I modified the rules, to make them easier to accomplish. I also cut them right back to the level of what the kids were doing anyway.
Now, we do have important rules - the most important ones are - we are a family, we work together as best we can. This means working towards good self-care and also where possible, working together to help others in the family (such as chores to help get dinner, feed pets, do something for someone else when they ask if you expect them to do things for you when you ask). Reciprocation. These things have natural consequences as 'punishment' - if you won't stir yourself to help your mother, then she will be too tired to fix your favourite food.
The next important rule - don't disadvantage anyone else in the family. Or if there is no way to avoid it, then disadvantage people as little as possible and make amends where you can.
These rules round very abstract, but they have concrete ways of expressing them so a little kid can understand.
The younger the child, the more they cannot follow these rules. A baby will make a huge impact on the household, inconveniences a lot of people, makes people tired, makes a lot of work, cannot self-care. A difficult child will, in various ways, be like a baby. So you work on the stuff they can do, and leave the rest (no matter how unreasonable this may seem to observers).
To help you with this problem - I think you may need to take some time for yourself (and with your partner if there is one) and analyse your rules. As you do this, try to find the natural consequences. Look also at the rules she is consistently breaking, and see if, at least for a while, you can find a way to do without those rules.
Obviously some rules are vital - we have an important one, "no food in the bedrooms". I have had at times to stand there and watch the kids eat at the table, or maybe on a plate on their laps in front of the TV. But not at the computer (because food and drink can do damage) and not in their rooms (because the slightest trace of dropped food makes a mess and brings in vermin).
In their teens, the older kids broke this rule. easy child 2/difficult child 2 had a bulk bag of jelly beans in her room. difficult child 1 had bottles of soft drink in his room. And the ants found both. Natural consequences - the kids had to deal with an ant plague, and their father's extreme anger at having to deal with the problem in a hurry. And they saw, first hand, for sure (so the message and the CONNECTION got rammed home) that the ants were their fault because they broke the rule and had food in their rooms. They finally understood the WHY of the rule. And now they live in their own homes, they follow that rule themselves.
Without being able to make that mental connection between the rule and the consequence, the kid will learn that punishment happens. They will draw the connection (especially if they keep breaking the rules for whatever reason) that they are being punished simply because of who they are. NOT a healthy lesson.
In the long-term, you need to get this message across, that rules are important. But if you have a difficult child, the usual methods often not only don't work, they backfire. But other methods do work, sometimes you have to go back to square one, to the baby stage, and work from there. if she's definitely no longer a baby, she should progress back fairly quickly. But when you find the problems you have now - rules always being broken - then there is something not working. Your methods are the problem - not that they should be, but it's because your child is not typical. Your methods might be gold card rules in the best parenting books, but for REGULAR kids.
The advantage with this different approach - it works for all kids.
It's like the meals thing - I no longer stop difficult child 3 from snacking, even on rubbish, even if it's only a few minutes before dinner. Because I KNOW, in his case, he WILL eat his dinner. he happens to be a walking appetite. I've seen him start cooking something for himself to have for lunch, when I had a meal already set for him on the table and he hadn't even looked. I'd even called him, but he had forgotten.
So he goes and eats the meal I have out for him, then when the meal he's put in the oven is done, he eats that too. Maybe in the middle of the afternoon. Then at dinner time - he still eats all his dinner.
He's as thin as a rake, I don't know where he puts it. Nervous energy, I think.
so one rule we've dropped for him - "no snacking between meals" because we KNOW he doesn't seem capable of ruining his appetite.
But at the same time and in the same home, we had to have a "no snacking" rule for easy child 2/difficult child 2, because she eats so very little, she's never hungry. I had to make sure that any snacks she ate, were what I would have given her for her meals anyway.
Sorry to take so long - I've had a very interrupted morning, it's taken me about four hours to get this response finished (when normally I could put this together in ten minutes). I hope it's not too disjointed!