What's going on with my cycles!

Hello ladies, I'm new to the group! Very concerned with my cycles. Need some advice please! I've always had 28day cycles lasting 5 days with period. After March of this year my cycles have been all over the place. Now they are 27 days, 26 days and 25 days. It keeps changing every month, and it's making it even harder for me to conceive, which I have been trying to do since December 2013. Any feedback as to what might be going on? I'm 35, and I'm trying to conceive my 3rd child. Please help? Thanks