Well, I've been in your situation before. I'm thinking that you should get to know her a little better. You may have sent those "i dun wnt u" vibes and that's not good. Now because you have feelings for her, it may take a bit of courage on your part and I know this isn't going to be easy. You should begin casual conversation again, maybe apologizing for being a bit terse when you were (everyone loves people who can admit wrongdoing). After this it might removed some awkwardness that may have been there prior because of this.
Maybe in some time you can take the time to pull her to the side and have a conversation, not letting her respond with a 1 to 4 word response. Engage her, talk about things she likes, what she's doing, and learn about her, as a person. Doing this can get you on a road to where you may want to be headed.