Low HCG...nervous

I got my first bloodwork done on Monday. HCG was at 75 and Progesterone was at 5. Doc prescribed P supplement and retested today. HCG is 145 and P is up to 18. Good increase but still low HCG. I am 5 weeks today. Anyone else experience low HCG levels and have a healthy baby??? Could the P supplements just be prolonging the inevitable?! I'm so nervous! This is our 4th pregnancy and due May 16th. 3 miscarriages in 2013-14. Picture is how I told DH when he got back from deployment to Harvey!