Were you on birth control before? If so, it can take some time for your body to get back to normal.
Also, five months is not a long time for you to be trying to get pregnant. Most doctors will not consider you infertile until you have been trying to become pregnant for eighteen months or more.
Another thing to consider is the fact that your husband smokes marijuana. Marijuana can lower the amount of seminal fluid and the amount of sperm in that fluid; and the sperm he does have can be abnormal. So he should stop smoking pot.

I'm not sure if smoking pot does anything. My best friend was on birth control for many years. She got off and got pregnant within 2.5 months. She doesnt do anything, but drink here and there, but her husband smokes pot everyday. On the other hand, my first cousin. She use to do drugs. She would drink here and there, smoke cigs, she would also do coke, and take many pills. She got off her birth control (didnt stop doing drugs) and it took her 8 months to get pregnant. Yes, once she found out she was prego she stopped everything (even smoking cigs). And again, myself I was on birth control for 5.5 years. I got off of birth control (I dont do drugs) only drink here and there and smoke cigs. I got off birth control Dec. 08 and I got pregnant July 09. So it took me a while to get prego too. My husband drinks if not everyday, but every other day (he's working on stopping now). I of course do not drink , nor do I smoke (thank God), so I think it just depends on your body. I do believe it will help your chances getting pregnant if your husband stops smoking pot. Drugs/alch etc does effect the mans sperm.