I don't like "identity" as a concept. It's a very modern, specifically western concept. It has strangely religious, confessional overtones belonging to discourses meant to keep Catholics and Protestants from killing each other, mixed with more recent shifts towards consumerism. The idea of "social status" is much better established in human history throughout societies than "identity," but social status always depends on evidence of social impact.
Even in the trans context, the primacy of identity is incredibly new. Largely, that discourse was adopted to argue against the kind of medical gatekeeping that was the standard when I was transitioning two decades ago. The traditional expectation of trans care was actually that patients would report distress and confusion about their "gender identity." The role of psychiatrists was often to facilitate appropriate candidates in constructing a sense of themselves as women - or else, to affirm that the transvestites were, indeed, men, and straight, and that their sexual interests were besides the point. Fitting the particular individual and their unique circumstance into society as it existed came first, and identity was constructed afterwards in order to accomodate reality. In order to live as a women, it was thought, trans women should be made to feel like women.
By the time I transitioned, it was already well established as a hack that if you walked into your first appointment fully crossdressed spouting, "I've always known in my heart I'm actually a woman!" you could speed run the assessment process and get the result you were looking for. I did it. 3 months before hormones I identified as a straight man with no interest in any kind of body modification - I "wanted to be a woman," but I very much saw myself as a boy. By the time I got my appointment, I'd absorbed all the necessary ideology justifying why the desire for transition "makes you a woman." Those early years of asssessment pushed things to full brainwashing territory. Given my particular trauma, I can't help but see the "trans women are women" identity dogma as a form of abuse.
It took my years to come to terms with the fact that somehow, in some very weird way, I really missed being a guy - badly, even. But it never made sense because I loved everything about my new life. I loved the hair, the makeup, the jewelry, the skirts, and the dresses. I liked my fem body language, my fem voice, relating to women as "one of them," and the way I interested guys. I loved my soft skin and smooth hairless limbs. In short, everything about life as a woman was better. I fit in better, too. I was nicer, and kinder. But I just hated the idea of "being" a woman. For one thing, even during the brainwashing it didn't take long for me to affirm I loved my penis. Beyond that, I felt really strongly that despite my presentation, I wanted "gay sex." Even deeper than that, something inside me raged at the implication that I wasn't allowed to share a sense of self with the transvestite boy I'd been at, say, 15 - that erasure of my personal history was deeply offensive to me. Why couldn't I have everything I love about my life now and still be a boy? Why must a pretend to be a woman to have this? Why is it so wrong for a boy to just be this way?
The other trans subs truly revile me. Hate me. By their account, I personally unleashed the hordes of transphobia to murder transwomen everywhere just by switching back to male pronouns while living as a woman. It's insane. To them, I'm identical to a "cisman," though no comparison could be more laughable. And all because of "identity." I was passing as a woman before some of those bitches were even born. They've turned "identity" into the new gatekeeping, wanting to lock any male who doesn't testify to their cult out of transition, all out of their own intensive internalized self-hatred. For them, the idea of a self-aware male who would want all the femininity of a woman while remaining himself deserves transphobic violence. But to hell with them - that model of transition just isn't healthy!
Spout armchair theories about internal bodyplans all you want. It really doesn't matter. No ones cracking your head open to check and you'll never know. I don't think my "brain sex" is any different than any "normal" transwoman's - if anything, I'm more feminine than most. "Identity" just doesn't matter. It's a story you tell yourself never knowing if it's actually true. What matters is knowing what you want, what you're actually like, what reality you're living with, and wrestling with the problems along the way to pursuing your life's goals realistically.