I just came out to most of my friends a few days ago. At first, most of them were a little confused due to how... sudden it was. I'd never really dressed feminine, or anything like that. I guess they attributed the way I acted to my watching so much anime and being an introvert. But, after a little while, and after me explaining it to them a little, they seemed pretty cool with it. All of them accepted whatever made me happy, and that's saying a lot -- considering me and most of my friends are in the 12-13 age range.
The one thing that /has/ been rather demoralising is, due to my age, every doctor I've seen so far has essentially said "It's prolly a phase, bye." -- however with that said, the doctors I've seen so far haven't known much about these kinds of things, so we'll just see.
Good luck~