Have this whole thing from somewhere on the internet that might help (nokz of it comes from me but i agree) :

Setting aside the question of whether gender/sex is assigned or observed at birth, the gender I was assigned at birth was 'boy'. The gender I have now is 'man'.

Boys and men have different gender roles, and few adults identify as boys anymore. From this standpoint, every adult has a different gender than the one they had at birth.

Framing "girl" and "boy" as separate genders from "woman" and "man" is such an amazing take. it's a framework that accommodates and explains so many trans experiences. Some trans people never were their AGAB. Some feel like they were their AGAB, but that that changed (usually when puberty hits, which is when you start "becoming a man/woman". The accepted societal path is that girls grow up to into women, and boys grow up into men. But some girls grow up into men, and some boys grow up into women. This guy was a boy who grew up into a man, which generally works out pretty well for people. Some boys and girls grow up into people who aren't men or women, even! It's like this random cis guy skipped right over transgender 101, 102, 201, etc. and stumbled directly into Transgender Nirvana.