Progesterone levels, help.

Cecilie • 25 mom of one baby boy whose name is Knox Maverick. ❤️
My doctor called me this morning and said my progesterone level was at a 15 and she liked to see it at 20+. I am only 4 weeks 4 days pregnant. Does this mean I am going to miscarry? She prescribed me a progesterone supplement. Please ease my mind.