Heart rate at 15 weeks

Hi everyone!

Just had a prenatal appointment yesterday at 15w2d with a baby boy and the heart rate was 140bpm.

When I was earlier along, it peaked around 180. I know it supposed to slow and plateau the further along you get but this is seeming slow to me.

Has anyone had a similar heart rate at 15w? Doctor wasnt concerned and said heart rate looked strong but im a textbook overthinker and could use some reassurance

Thank you!