10 weeks today

At my 9 weeks 6 day check up they couldn't find a heart beat on the doppler so they checked with the ultrasound. Found the heartbeat at beating at 167. The tech told me it was hard to find because the baby is so small. That kind of worried me. Then she just left and I was done with my appointment. Anyone else have this problem. I am small so maybe the baby is just small like me. This is my 3rd child and never had this problem before.