How to tell if this shy girl likes me?

So I'm in high school. I play sports for the school, and I'm a pretty good looking guy (not to be conceited at all). There's a girl that I really like; she's on the cheer team, and is very beautiful. However, she is also extremely shy. Whenever I try to talk to her, she seems a bit apprehensive, but also is always smiling, albeit the conversations are quite short, since we rarely have much time to talk in school other than ping periods. We also go to a very small high school, and I'm afraid that if I am rejected, if it would be awkward since our families are pretty close. I don't know if I should ask her out, or wait until I have a more positive look on the situation. However, I do know that she is competed over between a few guys (who I know she doesn't like, but I don't want to wait until one that she does comes along). What do you guys think?