10 points for best answer: I think I screwed up with this girl, what do I do?

From the point of view of a girl, you didn't screw up by any means; just relax and text her in a few days to see if she wants to talk. Also, if you see her and have any classes with her, chat her up a little playfully/jokingly so there's no pressure of anything serious for either side. If she blatantly avoids you though at either of these attempts, I'd say the operation is a negatory, Ghostrider