Multiple miscarriages

I have 2 children one is 11years old and one is 5years old. I had no complications getting pregnant or with delivery. We got pregnant again in 2016 and had a missed miscarriage I was 11weeks but the baby passed at 8weeks. I had to have a d&c done. We started trying again march 2018 couldnt get pregnant. Until September 2019 and we had a miscarriage at 4.2weeks, then another on November 2019 at 4.3weeks and then another January 2020 at 4.5weeks. I have checked my progesteone levels and checked for lupus all came back good. Had a us to check my uterus and overies all came back good. What could possible be keeping us from getting pregnant and keeping the baby. Has anyone went through something similar? I have never been on birth control and me and my husband started taking fertility supplements.