Need an opinion about OPK chart

My SO and I decided we would try for a baby this month. I quit my birth control pill mid pack (ortho tri cyclen)  on October 21 and got a period/withdrawal bleed October 23. Since I have been on birth control for around a year I have always had 28 day regular periods. I bought cheapie opks and have been charting them. However, they were getting pretty dark for a while, and now they are getting light again. Did I ovulate and not notice? Or should I keep charting just in case? I know I am only on cd 12 but I'm worried cuz they are becoming lighter.