missed miscarriage - any warning signs?

Kind of a long question but here goes. I had a missed MC in August. I was at my 11 week scan and there was no heartbeat and the baby measured 10 weeks. It was my first appointment so I hadn't had any blood work or ultrasounds earlier. My question is, if I had an earlier ultrasound, would there have been warning signs? Would I have already been measuring small or would my levels have been below normal? Reason I ask is I'm pregnant with my rainbow (hopefully!) I went in at 6 weeks for blood work and levels were normal and went for 7 week ultrasound and everything appears on track and we have a heartbeat. I'm trying to be super positive but given my last experience I feel like these next few weeks will be very stressful! Any thoughts appreciated!