I am so sorry for your loss. There's no words to express the empathy I have for you right now. I just lost a pregnancy too. I finally had a D&C a couple of weeks ago after waitingfor many weeks to miscarry naturally. I heard the heartbeat at 8 weeks, and at my next appointment when I was supposed to be about 12 weeks, found out that the baby's heart stopped about at about 9 weeks. Don't blame yourself. Whatever you do, don't blame yourself. I know it's hard not to. I go through times when I can't stop wondering what I did wrong. And it makes it worse knowing that there was a heartbeat even if momentairily. Remember that the miscarriage could have happened for reasons other than progestrone levels.
I really feel for you. No one knows how it feels to lose a dream like having a baby unless they've been through it. But remember, if you want, you can try again. Just don't beat yourself up over this. Get lots of rest. Talk to someone about your feelings, maybe another woman who has been through this. And greive enough so that when you are ready, you can try again, and not have those guilty feelings hanging over you.