Hi there, you have your hands full. Is your son in early intervention? Are you in the USA? Your son being on the spectrum means the world really probably is all about him and it is not a character flaw, though it can really look like that. He is not purposely trying to steal all of the attention, or being selfish, he just does not get the other person's perspective and at his age alone, it is uncommon to really not be "selfish". Kids on the spectrum fall apart for many reasons. So, to help us help you can you share more about the evaluations and interventions/therapies you have had so far?
1. Have you had an Occupational Therapist (OT) evaluation?
2. Have you had any comprehensive autism evaluation ?
3. Is there an autism program (in addition to the public schools) in your area? There are several where I live and my son's insurance paid for him to go for preschool through Kindergarten... he went there 1/2 day and then the public school for the other half.
Here is something that is really hard, so I will just share it with you, but know I am still working on this myself... When you say that he tries to get his sibilings in trouble... it may be so, but if he is on the spectrum, and at his age, it is more likely that he does not have the social skills to do better. The hall monitor personality is because he is a rule follower I would guess, very black/white thinking. Most kids with autism need each skill to be directly taught and then help generalizing the skill into different situations. It is slow methodical work.
With the other little ones you have very right to feel overwhelmed. Are you single? Do you get any support at home? We have other moms here who can really relate .... they have kids with intense special needs and little ones too. I personally feel that the terrible twos is a misnomer... I think 3's are much worse. Clinical trials/medications probably not gonna be tons of help. What does help is to have therapeutic guidance specialized in the area of autism. Traditional behavior modification does not generally work with difficult child's especially kids on the spectrum. THey need their sensory, motor, learning, social skills all coordinated into one program.
If you can share more, we can share more ideas with you.... for now, please know, we get it... I can tell you that I for one can totally appreciate the frustration and feeling at the end of your rope! Hange in there.... realize that he is not purposely trying to hurt you (I do believe this strongly but also get how it feels like that!) and he is trying his best to make sense of a world that does not feel, look, or maybe even smell like it does to us. If he had a neurological challenge with walking, we would not say he was choosing to be carried to make it so the other kids can't be carried. But for invisible disabilities like autism, adhd, mental health issues, it is really hard to realize it is the same for them. When a child melts down like that, they are miserable. They would much rather be in a happy place. They can't do it on their own, but I think it is too much to ask for us to figure out all of it on our own. I work in early intervention and still can't do it on my own. I always need someone else to look in from the outside and help me sort through what is going on.
Check in frequently, people here really do care! Vent all you need to, this is not an easy job for sure!!!