Lol, sadly I've got anxiety when it comes to oh, I'd say--80% of people. Sometimes things click and I have no problem carrying on a conversation, and other times it's just weird and awkward.
Anyhoo, since I'm pretty much determined not to spend my life on the fringes of society, I took some advice I heard. It sounds kind of lame, but it helps to pretend to be confident and outgoing.
It takes some concentration but pretending to be the person you wish you were really does help. Just say and do all of the things you know you would do if you weren't shy.
Good luck with this--besides, you're already halfway there considering she conversed with you; believe me, the majority of girls don't waste their time if they're not interested.