Kimberly, there isn't anyone that can "stop" you from transitioning except you. I don't think it's a question of not being "allowed" but more a question of will you do it. You seem very sure in the fact that it's something you really want to do, and once you are over 18 (if you aren't already) you can make your own decisions, and take the first steps toward that goal.
Some people have asked, "why not just live as a gay male?" and the answer is simple... I'm NOT a gay male. I won't even have a relationship with a man until I have had SRS so that I can have it the "right" way, as a woman. I have even heard that many post-op M2F end up living as straight women even if they leaned more toward females pre-op.
In short, don't listen to people who don't know what they are talking about, as they are most likely going on misinformation or their own misguided theories. Move at your own pace, and do what is right for you, not anyone else!
You are already a beautiful young lady in my eyes =]