Two Early Miscarriages in a Row

Hello,
I am a healthy woman in her early twenties and my husband and I (who is in his mid twenties) are currently TTC#1. We have been trying for two months now and each month I did in fact get pregnant, both times with pregnancies that ended in very early miscarriages. Around 13 dpo I had blood work done and my progesterone was only a 4 (hcg level was only 17). I have a follow up appointment with my doctor on Wed. who thinks I may have a luteal phase defect. Any thoughts? Has anyone with such low numbers gone on to have successful pregnancy? Getting pregnant doesn't seem to be my problem right now, its staying pregnant that I can't seem to do. Also, I still have my progesterone suppositories left over and was considering ask my dr if we could try again right away this month and use them for the latter half of the cycle w/ the help of BBT and OPK. I think he would like to start me on clomid but by the time I see him it will be too late in this cycle to start it.