Baby's heart rate always 168

This may be a stupid question but my anxiety is at an all time high with this pregnancy! I'm currently 10 weeks 1 day pregnant. I had an ultrasound at 8.5 weeks, baby measured right on time and heart rate was strong at 162. I bought a doppler last week and have been able to hear the heartbeat consistently for several days now. I always find baby in the same place, lower mid/right side. And baby's heart rate is always the same - 168 to 170. I've read that it can fluctuate quite a bit depending on baby's activity level, but mine is ALWAYS the same. Just wondering if this is normal for how far along I am? Anyone else experienced this? This is my 3rd pregnancy but I didn't have a doppler with the last two and that was over 5 years ago! Thanks in advance!