Doppler Question

I’m aware they may not be accurate and I’m not worried. I got one because I have a SCH that has and still does produce a lot of blood which is obviously scary during pregnancy. I check every few days just to see if I can find the HB yet. I’m assuming I would almost always hear mine and then hear the baby if I’m in the right spot. I’ve had 3 ultrasounds where I’ve heads the baby’s HB. It was 150 at 7 weeks. 144 at 8 weeks. I’m 10 weeks now and a week ago my Doppler came. It’s a Sonoline B. The only heartbeat I was finding was 133 and it would sometimes drop to a 125. When I told my husband I heard my HB and the number, he said that seems high. It would be too low for the baby, right? Tonight, I picked up one that stayed around 80 but in a certain spot it was going between 125-133. It would start at 133 and work it’s way down a little each time. I’m just confused lol The 80 I’m assuming was me but then why would it jump to 133...and if that’s the baby at 10 weeks, shouldn’t it be higher?

Again, I’m not worried I’m just trying to figure out what I’m hearing or see if the machine may be totally off if the numbers don’t make sense. This was bought for fun and some reassurance and I’m well aware I’m early yet and may not hear anything for quite a few weeks yet.