I'm tired of this I don't know what else to do!

Im having another chemical ladies. Since my stillborn I've had 2 miscarriages and like 3 or 4 chemicals. What am I doing bad or what. ? Have anybody did something different and get pregnant with a viable pregnancy ? I don't know if is progesterone levels or what . My pregnancy test star really good and then the line gets lighter and boom Af . This is heartbreaking I'm done. I don't want to tray any more the last two chemicals were one 1st of January and now I'm on another one feb 2 . Please help me thanks I appreciate it 🙏❤️