I'm super shy,how to get out of my shell?

I'm 13.I've always feeled like an outsider everywhere I go..I get straight A's,I am about the only good student,I have never gotten in trouble at school..At my school-everyone is so loud,they have confidence..I'm shy at school but I'm really a loud person..Ive always been the nerdy girl..I've never had friend until the past school year..Im a tomboy and I mean I Burp like a grown man,I'm not prim and proper but everyone thinks I am...How can I stop being an outsider and be myself??Thank you..