If you've gotten pregnant after a D&C

Kate
So I had a D&C after a miscarriage.. it was only a sac and was only about 6 weeks so I figured my levels would drop quick. Had the D&C oct. 28th, about 3 weeks ago. Was feeling weird all morning so I took a test and it's positive. Is it possible that I'm really pregnant already?? Or is it probably just HCG still in my system? Thanks for any advice!