Clearblue digital ovulation

Ive been using clearblue digital for several months now and I encountered something I haven’t seen yet. I was getting the flashing smiley for 5 days then it went to the blank circle (low infertility) without hitting my peak. I decided to keep testing and got 2 more days of blank circles now I’m getting flashing smileys again! Two days in a row. Is it possibly I didn’t ovulate yet? Should I keep testing? Its CD 20. My cycles have been about 35 days long since my MC in January. Thank you!