Does she consider me just a bit of drunken fun or are her feelings for me stronger that that?

I think she was just nervous because if it all went embarrassingly wrong, she was risking losing your valued friendship. I don't think you're just a bit of fun to her, I think she has genuine feelings for you so if you have feelings for her then you'll be a happy household. If you do not return these feelings then you must never let this happen again as that would just be disrespectful.