I was talking to my sister Cathy about how to measure progress and she said she is in the same place with her fibromyalgia. She too has a few days that are not good, then better days that show improvement, and she has a sense of overall improvement.
What I notice most right now is that I am willing to go to places where I have to sit for a while, even when there isn't a large space in front of me. I find that I do not stiffen up as much when I get up and there isn't as much pain. It isn't definitive progress, measurable, but just the fact that I have discovered that I am more willing to chance these situations suggests that my body knows something is better.