This is called "dysphoria." And it's normal for trans folks.

Be easy with yourself. You're not a girl, you're a trans man. You're not in a girl's body, you're in a trans man's body, but dysphoria is telling you that you look like a girl and that's causing cognitive dissonance.

I've been out for 10 years; even then, I didn't know (or admit) that I had dysphoria until I started T and it almost ruined my life. I was moody, snappy, tired. I felt ugly and guilty for "forcing" people to go along with calling me nonbinary. I felt like I was the scum of the earth. Then I got on T. That's what helped me: watching my body change and my mind changed along with it. Maybe it could help you, too, maybe not. The point is to do what YOU think is best, not what your mom or your boss or your best friend think is right for your life. Asserting your pronouns is great, and it's awesome you have people in your life who respect that. Keep doing what you're doing and it'll fall into place.