Not sure what state you're in, or what your school's guidelines are, but I finished up HS (10th-12th) as male. Meaning, nobody knew my trans status besides one social worker, and the principal. At the time I was living with my dad, and he's always been real supportive, so I just went in with him, talked to the social worker, and they enrolled me with my initials. If you could get one of your parents to agree to go in with you, and sit down and speak with someone, you may be able to do the same.