Hi firsttimer,
I recently had a missed miscarriage at 12 wks after seeing a heartbeat at 6 weeks. Apparently the heart had stopped just after the u/s - at 7 wks, but I didn't start to bleed till 12 wks. Thinking back I lost my symptoms around 8 wks too. Sometimes it just seems to happen that way and there's no reason. I'm sorry for your loss. It's a hard thing to go through.
Best wishes,
Rach