I could be wrong, but I think you have to be 18 before they'll prescribe hormones.
However, maybe you could get an androgen blocker to stall any further testosterone development, if you can you should do this ASAP. Every passing year, you'll grow more masculine and the effects of testosterone are pretty much irreversible. In general they say the younger you are when you transition, the more passability you'll probably have. But more importantly, it's better to start later in life than to rush into something you're not sure about.
The androgen blocker if you can get it, will stall development until you're ready, and if you decide not to transition, you can stop taking it and develop normally as a male.
I'm FtM, so I'm not really qualified to comment, but I'm sure the ladies will jump in and correct any errors I might have made.
Good luck.
Nero