TTC after Depo

I guess I'm just not ovulating. As you can see by the picture, I do not take a break in opk's and never showing an lh surge. I received my last and final depo shot March 2015, so 6 months ago. I know all about the side effects of TTC after depo, but I was late one week with my shot on my first child 4 years ago and got pregnant. No period, not trying. Went to get my shot and I got a positive pregnancy test instead. This time I am consciously stopping my depo, charting, and using opk's, and nada. Everytime I see the line get a little darker I get excited to test the next day, and it will be almost blank. Depo is bad stuff.. just so crazy that I conceived the first time when I did.