Not sure where you're located, but most doctors will not administer hormones to someone under the age of 18 without parental consent. I would not be surprised if some even declined to do it with parental consent, as younger transitioners are kind of a new thing for a lot of doctors.
I would see if you can contact your teachers/professors/any school personnel that you may have daily or regular contact with, and let them know that your name on the roster may be X but you go by Y. Get them using a male or androgynous name with you.
Are you doing anything that requires changing clothes? Gym class, sports, etc. That could be difficult. See if they have gender neutral restrooms or handicap restrooms. You could change in there, and use the restroom there if you don't feel comfortable using the men's. Often times, the nurse's station or health services will have at least one. It's worth asking for.
I think really it comes down to how you present yourself. If you present yourself as male, go by a male sounding name, wear a binder, etc. - most people are not going to think twice about it. If anyone asks you why you maybe look feminine, say you have a hormone disorder and that you don't want to talk about it. If anyone asks why you use the handicap restroom, tell them you have an illness and you don't want to talk about it. People are not entitled to know anymore about you than you're willing to tell.
