Can't get pregnant.

We haven't been trying to concieve for two years, but we have been having unprotected sex for two years with no birth control what so ever. We are now trying now that we are engaged. But I guess my question here is, should I be worried that I cannot get pregnant if I haven't already? I read that after a year of trying with no luck that it could be a fertility problem. I just started taking prenatal vitamins hoping it may help. Anyways please help :)