I was told by my OB that the progesterone does drop and they dont measure HCG or Progesterone after 8 weeks due to this. But you should talk to your doc to see if they are concerned. Your HCG results are wonderful. Mine were only 2700 at 5 weeks. My progesterone was 87. Just to give you indication with my first which I miscarried at 4 weeks my progesterone was only 14 and at 5 weeks it was 11 and I miscarried at 8 weeks. My Fertility specialist told me due to my low progesterone I may have miscarried. Your progesterone is still a good level... what does the doc say? I found a website which lists the levels that are in each Trimester... hope this helps.

Progesterone during menstrual cycle

Day 1-14
>1 to 1.5 ng/ml

Day 15-28
2-28 ng/ml

Progesterone during pregnancy

First Trimester 9-47 ng/ml
Second Trimester 17-147 ng/ml
Third Trimester 55-200 ng/ml

Edited to add, I have read that some girls take a progesterone cream to help... I havent but may some girls can let you know about it?