M.K.
It seems to me if you bled very heavily then the body did it's job of shedding your uterine lining quicker than normal. I would be more concerned about the cramping too hard to walk business of your question than the length of your period! After the birth of my kids, the first periods were very weird- I imagine the same is true after a d&c. You should certainly call your doctor if you are worried! You don't necessarily have to go in to get reassurance that it is normal or advice to get care if it's not. As for what cd you are on, I think you start from the first day of bleeding, not the last.