I am new to this!

I am having trouble finding out when I am ovulating I have no signs other than a dull cramp which I have on and off all the time bc of my endo. I bought ovulation sticks and have yet to get a positive line what is going on!!? I took the test 12 days into my cycle then again at 14 I got nothing! Not even a faint line! Can someone guide me a little I'm about to call my RE