trying ?

So me and my hubby haven't been extactly trying for a baby. (This would be #3) but for the past two years my period had started skipping, lasting longer then normal or just short. We have been having unprotected for 3 months and nothing! He is a heaving weed smoker and we had a miscarriage 2 years ago.. and ever since we have had nothing ! I'm worried it might be me. I have no cyst on my ovaries all test done on me.. can't find the reason. And I'm scared I'm not working correctly! Starting to give up hope