I'm the same way. For me, the whole clitoris area is too sensitive. It hurts more than feels pleasurable. Most guys that I have told that I don't like oral sex tell me that I just haven't had the right guy, with the right technique.

I sounds bad, but I have had many, many, men try. It just doesn't feel good. I just don't like the direct clitoral area touched. I don't touch it when masturbating, so why would I want anybody else to touch it? Luckily, I like plenty of other areas touched
Don't feel bad, I think your girlfriend probably feels the same as I do.