I don't think I started to be ashamed of/anxious about it until I had my first inklings of gender dysphoria around 11/12, when my changing body and new social pressures started to clash with my subconscious expectation that I would grow up to be a man. Plus my feelings for boys were developing at the same time, and I didn't know any way to be attracted to boys except as a girl. So things got complicated for me and I spent the next twenty years confused.