At the risk of muddling things further, I want to add that having a strong gender identity isn’t a prerequisite for being trans. I never had an experience that I’d call “feeling like a man” or “feeling like a woman”, and based on the positive response I’ve gotten when sharing this article with other trans women, I think that’s a lot more common than I expected:
IMO, the concept of gender identity is like the Bohr model of the atom. It’s a simplified abstraction that’s easy to explain, and it’s accurate enough that most people won’t ever need to dive deeper. But if you keep probing at it, eventually you’ll have questions that it can’t answer, but a more complex model can.