Progesterone Levels?

I am 4 weeks exactly today. I had blood drawn on Monday. The doctor called and said my hcg levels look really good at almost 300. However, my progesterone level was at 10.5. She said they like to see it at at least 12. They called in a prescription for me and want to recheck my levels tomorrow. Does anyone have any experience with this? This is my first pregnancy. I'm a little scared now and would appreciate any insight. Thank you!