I had sex the 2 days prior to getting a positive OPK & got pregnant. I never would have guessed I would conceive w/ that pattern! Don't wait to do it till you get a positive OPK! Also ask your dr about the MTHFR gene mutation. I'm taking extra folic & baby aspirin. Just some thoughts. This is my 4th pregnancy & it took months to conceive the other 3 times. This go around I got pregnant a month after getting off the pill.