Help with this girl! PLEASE!?

[Matt]

In highschool, i like this girl, who is the coolest girl i've ever met, where in the same social group and have the same friends but for some reason we have never even talked. i think she may like me but im not sure, im not good at this whole 'feelings' stuff. she's always next to me and my locker is next to mine. The problem is she is NEVER alone and we hang out in big but intimate group and im not good in large groups. i don't know how start talking to her. If i try anything obvious the rest of the group will spot it and just heckle us for 3 weeks (but i love em) and the alone time she is sometimes alone is when where at our lockers but that's only for like 30 secs. Help!
Thanks