Is it me or sex? IN DESPERATE NEED OF ADVICE

I feel terrible, but sex is so dull to me?? I feel and can get off by myself and when a partner fingers me, but anything else I just don't feel it. No matter how much foreplay, all the ground he's covering, or what position, I can barely feel sex. I'll be stimulated everywhere BUT down there. It's just this incredibly dull, barely there pleasure. Never enough to get me off. Not to mention oral which I never even feel at all! At first I'd believe it was my partner, but after a few I'm starting to think it's just me. Why can't I feel/ get pleasure from sex? Does anyone else possibly have this issue, or at least advice??