As I have seen Dr. Phil on his show say to men in YOUR situation, "Are You CRAZY!!!". If you are not compatible with sex before marriage, you NEVER will be after. IT ONLY GETS WORSE.
I would suggest that you dump her and move on to other women. THe trick is to find a REAL HD women, which is roughly 15% of the female population. If you find such a person, date them for 4-5 years, to the point where the infactuation stage has worn off, and THEN you will see the real women.