normal hCG, low progesterone

Ladies, I am nervous! I got my test results back today from my blood tests a week ago. My hCG doubled in two days (from 5700 to 10,000), but my progesterone dropped (from 10 to 8). I am starting progesterone supplements tomorrow but I am worried my progesterone has fallen even more since then and I am at risk of an MC. I haven't had any spotting, just some mild cramping still (I am currently in my 6th week) I wish I had know about this earlier this week so I could start the supplements sooner. Has anyone had an experience similar to this and what was the outcome? Is a week too late to be starting the supplements?