What Causes Lack Of Heavy Bleeding After Miscarriage?

I had an apparent miscarriage at the doctor's office this monday. She asked me to do a quantitative hcg on monday and another on wednesday, and gave some ultracet for the pain I was supposed to feel during this week. Monday hcg levels were 6800 and wednesday they were 9500. I have felt no pain, and have been spotting only when I whipe, but she told me I would have heavy bleeding like a hevier menstrual period. Is it possible it was just a blood clot and not a miscarriage?