I dont know if she is interested in me or not. Please Help...?

I need some advice, tips whatever i can get. I met this girl on myspace and we bagan chatting,on messenger, i then asked her if she would like to have dinner sometime and she accepted and said she was thinking the same thing. We started texing throughout the next 3 days and she would text me first thing in the morning saying good morning and saying she had erflies and all that. We went out on Friday night and had a great time, we were both laughing and seemed to really enjoy each others company. On saturday she wasnt talkative at all and then on sunday i asked her to lunch the next day which she replied to with it's a date. Again we had a great time but she still wasnt very talkative over the next few days. I wanted to ask her if she would like to get together this weekend and also if she would like to go to the Marine Corps Ball with me, she said that she couldn't friday but saturday was a possibility, and that as for the ball she would be delighted to go with me. She has still not seemed to want to talk to me and when we have has been really short compared to the first couple days we were texting and such. I can not figure it out to save my life, it is driving me crazy because i really like this girl, and all i want to know is if she is interested in me or not. I also told her that i really liked her a lot and hoped to continue to get to know her and see if anything became of it, she didnt really give a response but is still talking to me. Does anyone have any idea what is going on?