Ovulation question

Is it possible not to ovulate? If so, what would that reason be? I started my period March 23. It was a regular 5 day period. I began using my ovulation test on the 10th day (like I normally do). I use the clear blue easy smiley one. For four days in a row, I got no smiley which means low fertility. Since April 5th (4 days), I have gotten a blinking smiley (high fertility), but I have gotten no peak fertility yet. I am now on cycle day 17. Tomorrow will be 18. Could I still ovulate?