Have had 4 c sections

My husband and I have have 4 babies born via c section. We have now been trying for over 18 months and can not get pregnant again. I have seen my doctor have had so many test done and so far nothing showing there’s a problem. Just feeling frustrated and depressed that it’s never going to happen. I keep praying every month is our month and the AF shows up on time or last month was 11 days late and had 4 positives and 6 negatives all different times. So I just don’t know anymore and honestly giving up hope. Any one else have this problem