8 wk ultrasound, no heartbeat

Upon going in for our first ultrasound at 8 wks, there was no heartbeat. LMP puts me at 8 weeks exactly. Baby measured 8 weeks 2 days. Is it unusual to measure ahead if you're miscarrying? I've had no bleeding or cramping. Absolutely devastated. I miscarried in my first pregnancy last year at 4 weeks. I had to convince myself that this pregnancy was going to be different, tried to stay positive, but 2 miscarriages now, a year apart, almost to the day (only 4 days off). I am scheduled for a D&C on Monday. If anyone is going through something similar, might be nice to keep in touch for support.