Bleeding and pregnant (tmi)

I'm 6wks and 5 days pregnant. I've been spotting since Sunday. Went to the er, they said I could be having a miscarriage.. They did a u/s and seen the sac but no baby but she did say it just might be too early. The er said everything looks good, doesn't look like im passing a mc etc. But the only thing was my progesterone level was low 1.7. My doc gave me progesterone suppositories 200mg 3×s a day vag. I'm worried. And advise?