I keep having to go back for viability ultrasounds due to measuring behind. Last ultrasound Monday measured me at 6+1 with heartrate of 90. Wondering what y’all think of my HCG progression?

6/2- 21000

6/4- 24500

6/9 36,100

Next ultrasound is Monday. I don’t know what to think at this point. The doctor did start progesterone as I was on the low side of normal (12); can low progesterone cause slow fetal growth in the beginning of a pregnancy?