Well, my kids are still quite young (thank goodness) but I can tell you that it wasn't all that long ago that I was seventeen years old and without many friends. I was very shy in high school and, while I had many casual acquaintances, I was always too nervous to take that next step with people.
So, instead of focusing on socializing, I invested myself in learning the arts. And while high school may not have been the highlight of my life, it was the place where I discovered some of my lifelong passions.
After I graduated, I got a job in sales and learned to be more social. If you knew me today, you wouldn't believe for a second that I ever had difficulty making friends. I'm a happily married woman with two beautiful children and several very dear girlfriends....along with many other casual friends.
I guess what I'm trying to say is that your idea of the perfect high school experience for your daughter may not be realistic. Some people just aren't meant to be popular in school. It doesn't mean she's not going to have a fantastic life. It just means she's more interested in other things than she is in socializing...and good for her if that's the case. My suggestion is to try not to put pressure on her to make friends (not that you are directly, but she probably knows you worry about it). This is one of those things that you just need to trust her to deal with herself. Encourage her to get involved in sports or clubs of you want (as others have suggested) and tell her that you'll always be there for her if the needs to talk.
I know I can't tell you not to worry about her...that's your job as mom. But maybe give her the benefit of the doubt. If she says she just wants away from the "drama"...believe her. If she's having a hard time, trust that she'll come to you. She sounds like an awesome kid so obviously you've been doing SOMETHING right all these years. Have a little faith in that.... :-)
Good luck!
-S.