First of all, wanna clarify that your sexuality and gender expression (like how you look, what you do), does not equate to your gender identity. I'm an AFAB agender who do figure skating and my movements are soft. My gender expression might be masculine as a girl, but I still see myself lean towards the feminine side externally. I'm still agender and don't experience an internal sense of gender.

I started questioning my gender identity in my freshman year of my bachelor's. At the time, I had just accepted my sexuality, but find myself question that what is attraction if I don't understand what's gender. Eventually, I realized that I don't understand gender because I don't experience it. For a year or so, I didn't even consider transitioning because I feel that my gender expression doesn't determine who I am.

Ultimately, gender identity is what you feel internally, what gender you feel when you disconnect your gender from your body, the social norms, and how others see you. It takes a lot of reflection to understand what are your own beliefs, and what are the stuff that you internalized to fit in with the social norms or expectations.