Confused

Hi. Wanted to see if anyone could help me. I started having a miscarriage in the middle of April. The baby stopped developing at 5 weeks. I kept bleeding very heavily for another week, I was convinced I had passed the baby. I saw the doctor and got scheduled for a d and c. My procedure was the 24th of April. My hcg levels at their peak never passed 2800. My question is, howling after a d and c does if take for your levels to go back to normal? My husband and I had sex on this past Sunday and Monday. Today I happened to take a pregnancy test and it was faintly positive. I am wondering if it is because my levels still have not normalized.