A little confused here... o.O?

Alright so im 17 (almost 18) and I like this girl who's also 17 and we've gone on a few dates kissed and done things that you would normally expect people in a relationship to do, cool stuff right? The only thing is, now she seems to avoid face to face contact... I ask her if she wants to go somewhere or do something together but she always seems to have some sort of excuse. She won't even Skype with me or anything. We talk a good amount on Facebook chat and text a lot, but whenever I want to hang out again, she either changes the subject or feeds me another excuse... What's going on? She used to ask me to go places as well, but that's not happening now. Did I do something wrong? Is it just in my head? And I don't think I'm being clingy or anything because I only bring it up once in a while.... Help! :P