Don't give up on the big class professors. All it takes is one email, so email them all. If you got an A, you'd be surprised how many professors will remember your name, and then maybe pull out some old tests, go through them with you, and see where your strengths lie.
If you don't hear back, what did you lose? Also remember they may not be back until early September or whenever the Fall semester begins.
I was very much like you when I was younger, except I didn't sit in the back, I just never went, well when I did go, I sat in the back. When I went back to school many years later, I had to get involved and ask questions to keep my self interested. I highly recommend doing this. The classes go by so much faster! The professor loves it as long as it is not overdone, as we all too commonly see from the brown-nosers.