I think I'm going to tell her I'm old fashioned. Then get her fathers phone number. Then ask him if I can buy her with a goat.
This was way too funny!
While I am sure you are joking, I also feel it is my duty to clarify that this is a terrible idea - no women wants to be purchased for a goat... you have to offer at least 10!
Seriously though, it sounds like she might have changed her mind or at least needs time to think about it. The whole "it's not you it's me" thing might apply here - spring semesters are crazy busy and everyone seems to get a bit stressed out around this time. If she initiates a conversation, you can invite her for coffee again, but if not, let it go.
Next time you want to ask a woman out, just ask for her number. It is a more clear sign to her that you are interested and her response will let you know if she is interested or not.