Recurrent miscarriage

I have had 3 recurrent miscarriages before seeking IVF treatment. They were all in the first trimester and I have never detected a heartbeat. I was told this could have been from chromosomal abnormalities. I felt so much comfort having the PGS/PGD testing done when we got 5 healthy genetically normal embryos. They implanted one. When I went in for the 7 week ultrasound there was no heartbeat and I was told to stop the medication. This was my 4th time. I just don’t understand. There is nothing coming up in blood work or reasons why this is happening. I have no cysts, or polyps and told my lining looks great. Has this happened with anyone who has recurrent pregnancy loss, and have any of you gone on to have a successful pregnancy or have a reason why this happened that I should look into? I am at a loss and feel helpless.