Could I still be pregnant even after being told I had a miscarriage? My HCG dropped.

At the ER I was having some abdominal pain, and bleeding. That's when I found out I was pregnant. 2 days later my nurse at the Gyno said I miscarried over the phone, because my HCG dropped from 1468 to 485. A week later I went in for another blood draw to make sure my miscarriage is going the way it should, but it turns out my HCG went up to 762!

So I went in today for another blood draw, but I won't find out until MON. They also scheduled me for an ultrasound WED.

What do you think happened? What are all the possibilites?

My bleeding has stopped for a week without any pain!