Progesterone

Hello I am 4 weeks and six days pregnant I had labs done last week after finding out I was pregnant and I was given rogham for the negative blood type also they checked hcg serum on 6/1 and it was 42 and as of 6/3 it went up to 150. My progesterone they checked once on 6/3 and it was 7.9. My doctor decided to start me on progesterone 200mg once a day. This makes me nervous I've had some cramping prior to this and I had spotted from 5/27-5/31 which is why I took a pregnancy test on 5/31 as this is abnormal for me. Has anyone gone through this and have any insight? Thank you