Low Progesterone

Ka
I went in for my first appointment on Friday, and I had estimated I was approximately 6 weeks by my cycle. With my VUS, baby measured 5w5d and we heard the heart beat at 88-89bpm. My OB wasn't too concerned, so she scheduled a repeat ultrasound at 7-10 days to double check that the heart rate comes up. 
She called me this evening to tell me that my Progesterone is only 5.2, so she wants to start me on suppositories daily. I haven't had any bleeding and only very minimal cramping intermittently. 
Anyone had a similar situation with a good outcome? Anyone on Progesterone suppositories??