no positive opk

My husband and I have been trying for just over a year and a half and the last two months i decided to use opks to help with determining when I ovulate. We had tried to not use them or any aids like that for a while because I thought it just brought me more stress. I went to my doctor just after our year mark and had testing done for all sorts of fertility issues and according to my doctor nothing was wrong. In the last two months, i’ve started the opks the day my period ended and took them daily until i felt my AF symptoms coming on. But i’ve never had a positive opk. I’m getting annoyed that my testing came back fine but still feel like something is wrong. Any thoughts?