Hmm, let's see. I started testing again 2 weeks after my D&C. By the end of week 3 the tests were getting pretty faint, but then around week 4 they got dark again for a few days then faded again a few days after that. AF arrived at 5 weeks exactly after the D&C.
I did wonder if maybe it was a chemical, but AF wasn't any heavier than usual plus I was also testing with OPKs and they had been all over the place so I actually just think my body was really out of whack. I don't even think I ovulated that cycle to be honest.
It is possible you could be pregnant again if you are trying and if you ovulated immediately, but the only thing you can do is wait and see if the tests get darker/stay dark or fade.