^Well, girls do that a lot, especially at that age. I definitely think that she's trying to be a tease.
If I were you, don't worry about girls at your age right now. I mean, you seem like quite the mature kid, which is good, but relationships are not as deep as they are when you're older, so it's nothing but unwanted drama.
Take it from me: I didn't start dating until I was 18 and I've only had one boyfriend so far. True, there was some drama, but it was meaningful and I'm glad I waited to start dating.
You're not overthinking it, but you're getting yourself into a situation that isn't worth getting in.