After my D&C, I was still testing + for Hcg on OPKs for 3 weeks and 2 days after the procedure- granted they were medium/light in color, but still had enough color. But a week and two days after I had my lightest color OPK (it was negative obviously), I had a + OPK for 48 hours. We did DTD, but it had been 36 hours since the start of my +OPK and we didn't catch the egg. And actually, a week and half later I had my first period since the D&C, so the pregnancy would not have stayed. I was scared that my luteal phase would stay short and I would never stay pregnant again (negative nancy). I waited another two weeks and 1 day and got a positive OPK and we conceived our second daughter a day or two later when I actually ovulated.
Good luck!