I'm sorry for your loss too.
With my miscarriage it was at 9 weeks and it looked like the baby had stopped developing at 6 weeks. I thought it was from overdoing it too, but that isn't it at all- that may have just helped the first spotting start. I'm trying to say don't blame yourself- inarticulately.
Lots of hot baths, wine, and books on the subject helped me cope- plus other mamas on Mothering. As mamas here often say- be kind to yourself.
Book lovin librarian nerd mama to Caleb 6/06 and Aiden 4/09: and 1 angel 11/07. "No one cries alone in my presence."