confused

Hi all. 
So I'm 23 and my partner and I have been trying to get pregnant for about 3-4 months. 
I feel as though every month my fertile week is showing incorrectly and we're struggling to fall pregnant. 
I'm really curious can you ovulate a few days before your period is meant to be due??
My period is a few days late as it is, which isn't out of the ordinary but over the last 2 days or so I've had a fair bit of white vaginal discharge; does that mean I'm ovulating?? 
Thanks :)