I don't think you're doing anything wrong. I don't know how you were when you were her age but I really didn't want to hang out with my family and do "nothing" if I knew my friends parents were having a party. That far back it wouldn't have been for alcohol either just the fact that there would be and event going on and I wouldn't want to miss it.
I don't think you should be hard on yourself or her. I think you both are feeling "normal"
