I can't add much that is helpful in addition to what everyone else has said, other than that I can kind of relate.

I've a number of sexual issues that erode my confidence to this day. Like you, every time someone mentions sex, or even a relationship these issues come to mind, without fail. Undoubtedly these issues spill over into other areas of life. In fact, it might explain just about every thing that I notice in my behavior that could be called abnormal. The actual problems are cosmetic as far as I can tell. I'm a virgin(25 years old, and plan to stay that way until I get married) so I haven't had the chance to test everything in the real world.

With me, and it seems with you, we hold back out of fear. But we can't live in fear. It's hard to fight it, but I think you have to acknowledge your fear then decide to ignore it, kind of like "Damn the torpedoes, full speed ahead!" Anyway if you really put a lot into a relationship and really make the girl feel loved, then she will probably overlook sexual shortcomings(which probably are non-existent anyway). That's me totally hypothesizing, but it makes sense doesn't it?