QFT.

As many girls as I've been with who have loved looking at or being on my dick, in the end, it doesn't matter. Seriously.

Unfortunately, men of all statures are insecure about themselves; if we weren't, why would we need a website/message board to validate us? You two need to talk about it just once. Keep bringing it up and it's going to drive her away; you need her first answer to be the one that sustains you.

That being said, you're silly for having a gf in college. I say you go mix it up a little. ;)