First Ultrasound at 6 weeks 4 days

I had my first scan yesterday, and it was incredible. I heard the baby's heartbeat, and he/she measures .28 inches. Her/his heart rate was 110 beats per minute, which my doc said was perfect. This visit definitely made the pregnancy feel more real--I've been contending with a mixture of disbelief and apprehension about letting myself be truly and fully excited (because I'm worried that I'll lose the baby). 
I see this app says the heart rate should've been higher, but I trust my doc more than an app. I'm praying and keeping my fingers crossed that everything will continue to develop as it should. Doc said chances of miscarriage after hearing a healthy heartbeat go down from 15% to 5-7%.