Missed period

Last month I missed my period, and I don't think I'm pregnant. We've been trying to have a baby since February there is more fighting than sex. Last month we did t have sex once, the whole time we were supposed to have sex on fertile days we argued and nothing happened. It so stressful we have so much pressure from everyone, I am 36 and my husband is 37 going on 38. The past 5 years have been very difficult for me, with my mom getting breast cancer and them I got thyroid cancer, so pregnancy was not an option. Now that I am clear to convince it's so stressful. Last time we had sex was March 1st, then I hit my period on March 21st. I missed my April period, but now my breasts hurt so bad and I exhausted, I'm thinking that my stress made me miss my period. Now I don't know when I will be fertile to try again! Help me please, I need to relax but I can't.