Progesterone Levels 8 Weeks

I had a missed miscarriage in January and then got pregnant again in April. At my first appointment, 8 weeks exactly, the baby measured right on target and had a heartbeat of 170.  My doctor just called with the results of my blood work and said my progesterone is 16.4.  She said that is the grey zone and they want to see it at above 20.  What was everyone else levels?