It may just be tissue left over ffrom the d&c. I had one recently & I started bleeding bright blood about a week after the d&c, there is a couple of girls in my loss group that had the same thing, its quite common. A friend posted some info & it said that af is when there has been no bleeding for 20 days (not including spotting) anything before that is likely not to be af.
But it is possible to fall pg the d&c cycle, ive read lots of stories where people have. We aren't going to ttc again until next cycle, but ive been testing just to see if my cycle is going back to normal and its looking like I will ovualte again in a few days, so nearly 3 weeks post d&c