ANOTHER FAILED MONTH!!!!!

Yet another month of trying and only to get a negative . I have been trying to concieve for over four months now . It has been so frustrating and so hard, I feel like I want to stop. I'm only 21 , I get my ovulation and I get regular monthly periods ( no weird cycles). I thought it would be a little easier since I'm younger . My partner is also young like me and 😟 he does smoke a lot of marijuana. I'm wondering if that's affecting his sperm. I don't know why I can't get pregnant. I feel hopeless. I'm happy for the others that gets pregnant but I still can't help feeling envious. Why not me ?!!! ☹️