I have ADHD. As a child and teen I never felt I was a proper girl. It wasn't because of having traditional male clothing or interest likes, I was actually pretty feminine, but males and females are socialised completely differently still, and being someone with neurodivergent behaviour can leave you ostracised a lot more from female groups as the female socialisation just doesn't take the same. I think it's this that makes trans much more common in people who are neurodivergent.
I blurt things out, I interrupt, I forget and lose important things, as a child I was a risk taker, impulsive, bossy and argumentative. I don't have object permanence for both things and people like others do and I struggle with emotional regulation. Female social groups were a lot harder to navigate. There was much more talk of feelings and having to remember and consider how other people felt. There seemed to be a lot of drama and upset that didn't make sense to me. There seemed to be lots of unspoken rules I couldn't quite get a handle on, and I was often considered rude, because I didn't understand conversation in the same way and was quite blunt.
Boys were a lot easier to be with, they found the things I did funny and were more likely to join in, they liked talking about things like tv shows or random stuff rather than feelings. They didn't judge as much when I said something blunt, and would either challenge me in the moment or let it go. Interacting with them caused me less anxiety. For years I used to say to DH I didn't know how to do girl. I still feel like I'm not as good at being a woman as others are, and I'm not great at maintaining female relationships.
I absolutely would've believed I was trans if it had been a thing I was exposed to while I was younger, because as far as I was concerned, my brain and behaviour was like all the males around me and the women felt like they were different to me, a bit like a different nationality. I now know that's just because I have ADHD, and my brain works differently, but for years it made no sense to me why I couldn't just think and behave like the other girls could and I felt isolated and broken.