I'm so sorry for your losses...My dr. told me that they wouldn't do any testing unless I had 1 or 2 more m/c's. Lots of ladies haven't been able to be tested until after their 3rd.. I don't get it either, I wish things were different so that women never had to endure one let alone 2 or 3 losses...I wish you lots of luck and sticky baby dust.
firstly i am so sorryfor your loss,
i would try baby asprin, in small doses it's not harmful in early stages of pregnancy and may not work in some case's it's something i am keen to try myself, you may be m/c due to a clotting problem or it could be a million other reasons they just can't tell you or can't be bothered until you had several m/c which is emotionally traumatic for us, they treat us like another statistic but to us it's our baby we have lost our flesh and blood our loved one, but they see it so often i suppose, but it's not a valid excuse not to help.
you could have certain tests now like checking your partners sperm count and quality, checking both for any underlying health problems down there ie,infections no i'm not hinting on std's don't worry it's common to have the odd water or bacteria infection. i would also check both blood types see if they are a compatible match.
it also depends on whether your m/c due to a growth defect of baby, or through hemorrhage where the lining of your womb has broken down bringing your pegnancy to an early end, there are just so many possibilities, i have also heard of some women who have had their cervix sewn in early pregnancy to prevent m/c i think this is only when the cervix is too weak to cope with the weight of the womb.
sorry i have no miracle cure for you or wave a magic wand i would if i could, i wish you well in the future.