See... it's a decision that YOU have to make.
I have no problem with you having sex, as long as you take reasonable precautions--like birth control.
But--I'm Wiccan, not Christian. I personally believe you shouldn't EVER buy a car without test-driving it, and sex is a HUGE part of a marriage. MY beliefs are that it's STUPID to get married without having sex with your partner.
BUT--those are MY beliefs. YOUR belief system says that you should not have sex until marriage.
The question you have to ask yourself--because really, this is YOUR decision, in the end--is whether your religion is more important than your desire to have sex.