Baby's heartbeat will fluctuate based on their activity level. If they're sleeping it will be slower but when they're moving around it will be faster.
I agree with the other ladies and your doctor - this is NORMAL.
Heart rate should be between 120-180 bpm and depends on how active baby is at any given time. It will fluctuate between the extremes which is completely normal.
I agree with NicMom. As the baby gets bigger the heartrate will slow and as she said it also depends on activity level when heartbeat is taken. I would also be willing to bet that even the "minimum" as 120 is above what would really be cause for concern. there is nothing you can do about this beside keeping yourself healthy. eat right and drink lots of water etc. What you are describing sounds completely normal to me. Try not to stress too much. Good luck!
Don't worry about it. The heartbeat gets slower as the pregnancy progresses, but it can also vary depending on if the baby is sleeping or active. If I think back on the hb for my baby we were at 170 around 12 weeks and it's gone down ever since. When she's sleeping it gets as low as 130, but then when she wakes up and moves around it's back up to 140 or 150. I'm at 31 weeks now and yesterday the hb was in the 140's.
There isn't anything you need to do. It's normal so don't stress.