Help getting girl to relax and open up?

Well, she might be the type of person that wants the feeling of being liked, but doesn't want to go on dates with someone that is 10 years older for fear of being judged. If you know she likes you then you have nothing to be nervous about. Just continue to small talk. Because she's still young... talk to her. Become her friend first. Let her be completely comfortable and open with you before you ask her on a date. Then she may feel much more comfortable and the initial "intimidation" wil lbe gone. And you'll feel much more relaxed around her when you ask.