Low fetal heart rate

I had my ultrasound at what I thought was 6weeks 3days. From the ultrasound they measured I was at 6weeks. The heart rate was 61bpm. They told me it is possibly because the heart had just formed and I would have to come back in 2 weeks. I am super super stressed. To make it worse I don’t feel any symptom. Nothing. I am 7 weeks now. Don’t feel a thing except my boobs are a little sore. Just a little little bit.

Worried crazy! Anyone in the same boat?