It's possible you're pregnant. The only way to tell is to get the blood serum pregnancy tests and see if your levels are doubling.
Obviously if they're doubling, it's probably not residual HCG.
It's possible you could be pregnant and possible hcg is still in system. Mine was back to normal about 2 wks after d&c. Did you get it tested at lab after? Did you ever get a neg hpt? I o'd a couple of days after hcg was 0. If you didnt get lab work, I'd wait a few days and test again. If neg, I guess is leftover hcg. If is dark bfp, I would call dr and get beta done. Good luck!
You'll definately want to have blood work done to confirm if your levels had dropped enough for your cycle to start on its own. You RE can tell you by the levels of progesterone, estrogen, & HCG about where you are in cds and if you have ovulated.
Best Wishes,