does FSH levels fluctuate monthly?

Hi Girls

I would very much like to know if FSH levels can change month by month?
My FSH level recently was 15.7!!! eeeek! last one about 8 mths ago was 9 then year before that about 14.
Whats going on???

Im a bit upset as I was not expecting such a jump to 15.7 from 9 approx 8 months ago!
I understand the higher the level the less eggs left? that right?

Was it high because i took Provera to bring on AF? and actually this AF was very light and only lasted 2 days.

Will this mean I will be on higher doses of gonalF this ivf/icsi cycle?
Up to recently its been MFI in our case, but as time passes and me getting older I now feeling it could be me too :((

Any advice, encouragement and ideas to optimise my chances of success here most welcome