We have been unable to conceive for 2 years and my partner used to heavily use marijuana. could that be the problem? an how can we fix it?

Unlikely: Cannibas may lower sperm count but it is not permanent damage. There are a series of steps. A semen analysis need do be done and that may be the issue. Nevertheless I am unaware that past use has a lasting impact on sperm. Check ovulation predictor kit, make sure your ovulating. The odds are about 15-20% per month in couples without probs, we start an eval after a year, generally.

Ob gyn: See ob/ gyn. Needs medical evaluation for both partners may need to go to infertility cling let your obgyn doctor decide.