Could infertility be the only reason I can't get pregnant?

There are a number of reasons why you might not be able to conceive. Infertility in either you or your partner might be the reason but it is also possible that your timing is off. A woman ovulates 14 days before she gets her period, so if you have a 30-day cycle, you are probably ovulating around day 16 of your cycle. If you have a 28-day cycle, you ovulate around day 14. The unfertilized egg only lives for about 24 hours, while sperm can live in the female reproductive tract for days. So if you are trying to conceive, making love before and around the time of ovulation is more effective than after. Try an ovulation predictor kit for a month to see when you ovulate and try to refine your timing. Sometimes that is all it takes.