Hcg hormones after miscarriage

Patient: I had a miscarriage on July 17th 2014, my pregnancy was a blighted ovum pregnancy and I was almost 9wks along.Today, Aug 31st, I took a pregnancy test and it came back positive. Me and my husband did have unprotected sex in Aug. Can I really be pregnant only 7wks after a miscarriage, or is it residual hcg hormones from previous pregnancy? I’ve bled non stop since miscarriage, but only recently had it dwindled down to a light pink stain when I wipe after urinating. Any information would be helpful.

Symptoms: No symptoms so far.