Prepare for a very stupid question 
My cycle seems to be 31 days, and I would really rather it was the 'average' 28 days. I know it doesn't seem like much but those extra few days each month are agonising! Also it equates to 11,7 cycles per year rather than 13...
So, is there anything I can do to shorten it? Or is it just completely up to Mother Nature?
I can't think of anything... 