I am cd13 today. I have been using an opk since my period. First I was using the sticks but when my fertile window started i started using clear blue digital, the one that should give you the 4 peak days. This morning I got a plain circle, as I have every other morning. I did it again this afternoon because I don't want to miss anything and I got the peak smiley face. I never got the face with the lines. Any thoughts?