incomplete natural mc

How do you tell if you had an incomplete natural mc? I spotted brown for 5 days and then bled bright red with clots kind of heavy for about 3 days then it slowed down and I bled for another 2 days. It was a very early mc. I haven't been back to the doctor since I had my hcg level taken in the morning on the first day of bleeding bright red and it was 20. Later that same day it was 18. I am in the process of switching gynos and don't have an appointment until Friday. Please does anyone have any advice? This was my second mc. The first one was a missed miscarriage and I had to have a d&e because my body was showing no signs of miscarrying.