Home Doppler Question

So the heart doppler system I ordered online came in today and I tried it out. It was hard to find a steady reading. There was a good couple minutes where it was giving me high 90s reading but then it would jump to 175, 150 and 130. But twice it gave me steady 98/97. My heart rate was 98. Is it just picking up my heart rate?

Is it too soon to get an accurate fhr? I'm 10 weeks today. Don't want to freal myself out yet. It was 176bpm at 8 weeks 5 days.

Amyone use these?