Fetal heart rate question 1st trimester

I had my next ultrasound today, had extra this pregnancy due to losses and the fetal heart rate was exact same as it was a week ago. For reference today in 8 weeks 5 days (measuring 9 weeks) and last week to the day at 7 week 5 days heart was 178… well it was the exact same today.

At 6 weeks though it was 134..

Idk spiraling a little because isn’t it supposed to rapidly rise each week ?! Should I be worried?