Ultrasound... 😞

I just had an ultrasound due to brown spotting. Almost 6 weeks according to my last period. The lady told me she couldn't see a baby but saw the sac and asked if I wanted to do an ultrasound vaginally to see if we could see more. I agreed. She told me at the end she could see it but it was too small to measure. Is this normal or did it stop growing and am I about to go through a miscarriage? Waiting on my dr to call me but can't help but to worry.

Edit. Had blood work done on Friday. My levels were at 17,000.

Update. Baby is growing perfectly and has a strong heartbeat!