Hi Julia,
OCD is an odd beast, and it certainly manifests itself in different people in many different ways. However, the fact that this started when you were pretty young is probably quite typical for many (if not most?) of us on these forums. The fact that you've identified your current situation as being affected by what happened when you were young is probably right on the money.
That being said, you've already taken the right steps by seeking out a therapist. If you can, try to find one that deals with sexuality topics as well as OCD, as these two topics are obviously related in your case. OCD therapy is a slow process so try to go easy on yourself as you work your way through it.
Above all, you deserve to have the kind of love and intimacy you want with a man. There is nothing wrong with the concerns you have, and any doubts about yourself are a natural byproduct of your feelings. Your therapist will help you work through them in great detail. You might even discover other things about yourself that you didn't even realize were contributing to the issue(s).
Also, I can personally attest that there is nothing "disgusting" about sex. It's a very natural act for all living creatures, despite the stigma that society puts on it. The first time is usually the toughest for people (it was for me, at least), and for many people it becomes unpleasant only because of the circumstances they were in at the time (ie, they were drunk, too nervous, had to do it without getting caught, etc). But don't let that stop you - It's an absolutely wonderful experience with the right person, and I believe that part of the solution to your problem (along with the therapy) would be to find the right man who is patient and sympathetic to your feelings. It might be difficult to find him, but don't lose hope - he's out there somewhere. Just take it slow and don't rush into anything.
Good luck Julia, I really hope it all works out for you!