Having had two miscarriages ending in a d&c, My doc said to expect af about 28 days later. And yes count cd1 the day of your d&c. Anyhow, af came back at 35 and 36 days. Then within a few months my cycle returned to its usual 28 days. I think it takes a bit to get everything back to normal. It seems I tested positive on a pregnancy test up to 3wks after the d&c.
I'm so very sorry for your loss. I miscarried twins in February. I ended up bleeding for several weeks after my D&E. I'm not sure if its because I was 14 weeks, or if that doesn't make much of a difference. FYI, no one told me my first period afterwards could potentially be horrible. TMI, but I bled sooo very much. I woke up one morning absolutely soaked in blood. Hope this doesn't happen to you, but thought I'd warn you just in case. Many comforting hugs being sent your way.