What do I need to do?

My SO and I decided to start trying for a baby earlier this year. We actually conceived the first cycle but miscarried at 6 weeks. It's been 6 months since miscarriage and nothing. We've timed it with positive OPK's, we've BD daily and every other day during fertile period with a couple days before and after expected ovulation, I've even tried not tracking to reduce stress and just BD and have fun and still nothing.. How could I have been so fertile to get pregnant the first cycle and for 6 months nothing I try is working? I'm really trying to do it natural but I'm broken hearted every cycle AF shows up. I'm 41 and scared that time is running out for me. My cycle is so regular (26 day cycles) and all blood work came back normal. What do I need to do??