I think your biggest problem lie in self esteem.

You already are "good enough". We can all use improvement. When you stop searching for ways to improve yourself is when you stop caring. The fact that you do want to improve shows you care, but it doesn't mean you aren't already "good enough". She may be attracted to the fact she sees you making so many self improvements and still forging ahead to work on making it in school as well as financially too. I don't know how you look, but I do know a bit about your personality, and I do think there are a variety of reasons she may be attracted to you. She may, however, just want to be friends, or possibly looking to "test the waters" and see how things go. The only way to figure things out though is to do things like others have suggested - ask her to coffee, or lunch, or on a picnic ... somewhere public and informal but still not "usual" for the two of you. That way she doesn't feel threatened or uncomfortable in any way but the two of you can still get to know each other better. When you are with her, let the conversation flow easy. If you feel yourself getting irritated at all, switch topic, without any snide or rude remarks while doing so. Try to keep the conversation light and fun at least at first if at all possible.