why hasn't my fluency percentage moved in over a week?
I'm up to level 10, I think...
The only reasons I can think of are:
Duolingo feels like you aren't learning
A bug or a glitch
Or, according to Duolingo, you are forgetting words as fast as you learn them...
Your level is related to the number of XP that you have. They fluency percentage is purported to be based on the number of words that you know and how well that you know them. The relationship between the two is probably only tangential.
In French, my fluency rating stays the same for weeks at a time. My Spanish rating has gone down presumably because I haven't practiced it. Other people seem to have their rating go and up down frequently, but I'm not sure why that happens.