I'm American and I hated my CS program and university town. It was mostly immaturity on my part, but I had the same problems with US culture that you do which had a negative effect on my mental health. I would have preferred to be in Europe but I wasn't ready to live so far away from home.

You should go home, for the sake of your mental health. Especially if there is a chance that you could do a CS program in an European university. You'll have a support network there and you'll feel more comfortable in the culture. Do some growing up, then come back to the US.

If you do stay in the US, I recommend antidepressants and therapy (Don't cringe, I am speaking from experience here) Apply for CS programs at bigger schools like UIUC, U of M, or one of the U of C campuses. Stay away from SF until you've graduated.