I cant really offer any educated info, I found this thread very informative too.
I just wanted to wish you all the best and I know how sad and frustrating it can be.
I am pregnant ATM and the doc has put me on metformin to control blood sugar as I have PCOS (insulin resistance) apparently it is quite common to miscarry with PCOS. I thought it was just infertility but I gues I am the exception there, as I can fall pregnant I just cant stay pregnant. Metformin supposedly helps to prevent miscarriage.
Sorry I am rambling Im so tired.
I have two beautiful kids but ITS NOT ENOUGH I WANT MORE!!:P I am one of those greedy people that wants 4 kids.
So there will be hope for us, make sure you push for tests and answers as I was silly and just went with the flow. Make them look into it.
My diagnosis is only a guess so fingers crosed it works!
Best of luck!!