Heart rate

So, I went to my dr appointment last week to figure out exactly how far I am. They did the ultrasound and said it measured between 6-7 weeks. The heart rate was between 105-110. I've read online that's okay but my dr said normally it's fine and the baby is perfectly okay but in some rare cases when the heart rate is that low the baby will end up not developing properly. I have to go back on the 11th for a second ultrasound. I'm trying to not to think about it and just be positive but it's hard to do. With my last pregnancy I had a miscarriage (the baby stopped developing and I never got to hear/see the heartbeat). Have any of you ladies had the same experience? Was everything okay?