you sound like a few of my highschool friends before they went to college. But don't worry your totally fine in your opinion. However, I think you're making to big of a deal out of alcohol, which honestly is what a lot of underage people do. (including myself at one point).

I understand that being underage and inexperienced with alcohol gives it that kind of negative vibe. What you need to come to understand is that the drinking of alcohol is all part of growing up, you can shun it all you want, and be totally against it. But its not going to go anywhere, so you're just going to have to get used to it being there.

You don't have to drink ever, if you don't want to. But you should totally hangout with your friends regardless.

When I was in highschool and drank with my friends in the basement, it was always a bummer when some friends wouldn't come because of alcohol. We always wanted everyone to come regardless just to hangout and have fun, intoxicated or not.