Welcome, Stephanie. I strongly agree - get her evaluated. It can be expensive but a good evaluation can change your lives.
Do homework yourself, too. Keep some sort of diary of her behaviour. You've already made some valuable observations - she's a leader and not a follower; she's great fun when things are working her way; she doesn't cope with change; she's got some tactile/Sensory Integration Disorder (SID) issues. I suspect she's also very bright and has certain subjects she particularly is good at and enjoys.
This is screaming "Asperger's" at me, but there are other conditions which are superficially similar. and the tendency to Pervasive Developmental Disorder (PDD) in its various forms (the umbrella which covers Asperger's, among other conditions) is hereditary. This doesn't mean that all who inherit the tendency will display the condition - scientists are still working on that one. But it could connect to the family history.
You've queried ODD. In my view, ODD-like symptoms can result from trying to parent a child in a way that is not appropriate to that child's specific needs. This doesn't mean it's your fault - it happens, in some underlying conditions, that the usual discipline techniques which we've been brought up to believe in, which worked on you and which are great with your other children, actually make some children worse. And there is also the possibility of stand-alone ODD, which I consider to be separate. For now, I would recommend taking the Ross Greene approach - try and get his book, "The Explosive Child". As a start. Grab a copy out of the library, if money is a hassle. If it works for you the shop can always be there for you. Also, there is some discussion on this book on the Early Childhood forum.
I feel it's worth considering the following:
1) She feels a desperate need to control her environment, perhaps because for her, it's not as easy as it perhaps looks. Change brings unpredictability and uncertainty, which makes her afraid and anxious. Often these kids react to anxiety with anger and violence. It's a defensive thing - "you made me feel bad (anxious) and I'm going to be angry about it until you make it better." They often aren't equipped to recognise anxiety for what it is, especially if there's any Sensory Integration Disorder (SID) in the picture.
2) She's impulsive. Knows what she wants and will get it however she can. Determined. Stubborn. You can't block her and if you try, you get rages. Because SHE knows better.
(You get this in bright kids for whom the world is a confusing place - these kids have put a lot of brain power into developing their own understanding of t heir environment and how it works. This includes developing their own understanding of how people interact and how she can get what she wants from other people).
If I'm right, you need Ross Greene's book. A lot of us on this site have found it to be helpful. To be fair there are some who say it hasn't helped them, but from what you say I feel it should make a difference to you.
Make a list of as much as you can. Document, document, document. Write down everything unusual or interesting she did, from her earliest moment. Discuss this with husband and any others who know her, ask others for their recollections too. It's amazing how something apparently trivial or maybe amusing can also be enlightening - for example, difficult child 3 showed an affinity for trees from the first opportunity. I brought him home from the hospital and when trying to settle him, I carried him in my arms to the garden. I could see his eyes on the leaves on the tree and the closer the leaves were to his face, the more he seemed to settle. This happened every time and was even more noticeable in the west-facing backyard in the late afternoon - I realised later that it was the flicker effect of the sunlight through the leaves. He was stimming (self-stimulatory behaviour in autism, like flicking their fingers in front of their eyes - it soothes them, like stroking their arm.) And then a few months later he would be lying on my bed watching "Sale of the Century" on TV, as if glued to the set. he would get fretful during the ad breaks, then shut up and focus on the TV when the show was on. We thought it was funny, cute and it HAD to be coincidence - until later on, when it turned out he was hyperlexic. At only five months of age he was fascinated by the competitors' scoreboards. Then it was the display on the microwave oven as it counted down the seconds. His first words were the numbers he was reading. And letters.
A lot of this came with 20:20 hindsight. difficult child 3 was apparently a bright baby who loved music so I let him sit on my lap when I played the piano. I would guide his fingers on the keys but he never bashed at the piano the way babies often do - he would instead 'feel' for a harmonising chord. Eerie. I have a musically gifted cousin, I figured maybe difficult child 3 was following in his footsteps. Then I used difficult child 3's interest in letters to begin teaching difficult child 3 about the different note names. He got it fast and was reading music by about 2. By then he was able to name and type the alphabet, upper and lower case, into the computer and read a few simple words. But he still wasn't talking.
All this seems odd but not necessarily significant, until we put it together with what we know now - difficult child 3 is hyperlexic and high-functioning autistic. We've not been able to spend a lot of money on treatments, but we've worked out a lot for ourselves. There has been support at school and now we use correspondence school, he's doing much better. Because we understand where he's coming from, and he also understands that he is different and why, we're making good social progress.
Once they know it's not their fault, it helps a lot. They realise that life isn't fair, they've been dealt a raw hand and at first they really resent it. But we sold it to difficult child 3 (and also to difficult child 1, when he was diagnosed with Asperger's) as a condition which brings blessings with the disadvantages.
We've been told that difficult child 3's history of language delay means his diagnosis has to be autism, not Asperger's. Even though an assessment now would show no language delay ("within normal range" does not necessarily mean "normal for him, if he had no problems") it's the history that makes the difference.
Your daughter may have something very different, or it could simply be the sign of a wilful child who has not been disciplined properly. But if you have a son with no problems I doubt this is a straight-up discipline issue.
Something to give you a starting point for thought - check out the Pervasive Developmental Disorder (PDD) questionnaire on http://www.childbrain.com.
It's not officially diagnostic but it can help you get started. You can print the result and take it to your specialist (even your GP, if that's where you're starting) and it will show the range of things that are concerning you.
But whatever you do - keep a diary. Document. Try and recall history. And maybe talk to her about how she feels. She's a bright kid - she knows something is wrong and probably thinks badly of herself for being so difficult sometimes. Or thinks badly of everyone else, for always being obstacles to what she wants.
For now, your best coping strategy is to give her what she wants, if it really doesn't matter. Only argue about it (and no shouting at her) if it really is a big problem, like a major safety issue. Give her choice and control, where you can afford to. For example, if you want her to wear a sweater because it's cold, but the colour doesn't matter, tell her that she can choose which sweater to wear. SHE now has control but YOU have given it to her. She will learn to value you for that. This is not spoiling, if you do it right. It can be salvation and actually lead to a more cooperative child.
Further down the track - you will need a specialist who deals with this sort of problem (this will vary depending on where you live - for us it's a pediatrician) as well as a psychologist/counsellor for her to talk to and maybe another one for you. You also need her seen by someone who can review everything and give you some formal assessment, as well as an indication of what sort of help you can provide yourself.
Too often we look for either a "magic bullet" or a doctor who can wave a magic wand and turn our child into Miss Perfect. We want the expert to do it all. But it doesn't work that way - you need to become the expert in your own child. And to a large extent, you already are. Expert consultation is your tool.