It is very likely that you have O'd already. Did you have a BT to make sure your HCG levels had dropped back down to zero? If so it can basically happen any time after that. My cycles after my 2nd m/c (1st one last year) were a little shorter and I found I was Oing a little earlier than I would've expected. I've read that some women can O as early as a week after a loss, but the great majority are from two weeks onwards.