Fetus measured smaller than expected

Hello, so I currently had a miscarriage last August when I was 10 weeks pregnant. Never seen a heartbeat so they figured it was a missed miscarriage. Had a D&C done since baby didn't come out naturally. My periods were abnormal the last 5 months. I got pregnant again in January. I had my appointment today which was supposed to be my 8 week 4 days check up. Doctor said I possibly ovulated a lot later than what I thought and baby measured 6 weeks 4 days. The biggest she got the measurements to be is 7 weeks and 2 days to help comfort me a bit. Baby's heartbeat was super strong this time, beat normally. Although she stated that once we got this heartbeat it's rare to have a miscarriage again, I'm still scared. Anyone else go through this, how did things go for you?