10 week check up - Doppler no audio

I just had a 10 week check up with my doc and she used a Doppler to hear heart beat but I couldn’t hear it. She said the machine definitely picked it up and heartbeat was 141.. she said it’s normal not to hear it this early but I still feel a little worried. Anyone experience the same thing? 🙁

Ps I previously had a dating ultrasound at 7 weeks and baby had heartbeat