ovulation predictor

According to a calculation of my last three periods a nurse said that I should ovulate between 26-35 days since first day of period. The pic attached is from 29 days since first day of period to measure ovulation. I took it in the evening at around 6pm Which looks to me that I'm about to ovulate. That is with a dollar store ovulation predictor. Yesterday, 30th day I took it with clearblue and it came out negative. Today I took it again and it saids low fertility with the smiley face.