What Causes Shorter Menstrual Cycle After Failed IVF?

Good morning, I always had exactly 28 day menstrual cycles when I was younger. Then I had 2 IVF s in 2011 and since then my menstrual cycles are exactly 25 days. I had another failed IVF in 2013. What is the meaning of this shortened menstural cycle? I am also taking parlodel for a high prolactin hormone and my FSH is above 9. Please help.