I had the exact same fear. I intentionally chose a very large college. Why? Because the notion of being in a small class where I was expected to interact terrified me. I wanted to go somewhere that I could blend in and not be noticed. I also chose my degree (engineering) because I thought I'd have less interaction with people. That latter hasn't held true. In reality most careers involve significant interaction. But I did appreciate, for my first couple years of school, that my classes mostly had 40+ people, some much larger!