I don't actually know anything about those OPK tests so there may be another reason with them, but I wonder if you might be?
I started bleeding late on thursday 11th March, and had D&C on friday 12th. I had really one sided pains and stomach (more sensitive than normal) pains on tuesday / wed /thursday last week. So I decided that unless AF showed , that I must have been ovulating last week and tried to catch it. Have a new ticker , but completly guessing by dates from the 12th as first day of bleed and also my body telling me. Have decided unless we fancy it (as OH feels a bit under pressure bless him) , no point trying now, I think my window has gone! I may be completely wrong, but we are very close in dates you and I, so hope that helps you. Hopefully the bleeding will stop soon for you and you may have time still. If you miscarried normally and only started bleeding last week, then perhaps you have another week till ovulation? or I wonder if your hormones started dropping before the MC ?
Oh it's so confusing! Hope your bleeding stops soon