Results of first beta!~Doctor please let me know what you think!

Ok well my hcg level was 124 and my progesterone is 16. I’m told it is a normal progesterone but on the lower end of normal so my doctor wants me to start prometrium today. I’m really worried about the progesterone and just want to know if you’ve seen this in a lot of your patients doc? I guess I just need reassurance!!!!! I go for my second beta on Wednesday.