I'm concerned that you're developing oneitis over this one girl. She has been nice to you and you both had a great interaction. But don't start investing in her too much yet. You're reading a lot into things that might not mean much. I'm talking from experience. If you want her, then treat her exactly the same way as you would any girl you just met that you wanted to pick up.

She might like you at this point but you don't want to drive her away by thinking and conveying to her that: 1) it's a forgone conclusion that you'll be fucking her or 2) she has something special that other girls couldn't give you just as good.

Going from what you described I would let her do the running and chase you. When a woman get's in chase mode you have to let them play that role. If you act all eager it could kill the tension for her. I'm guessing here but I think that's what's going on.

Take what I'm saying with a pinch of salt but think about it.