Anovulatory cycle

Kr

Is it possible to ovulate without getting a positive opk? My lines were getting darker and then disappeared. I’ve been testing 2-3 times a day and haven’t gotten a positive. Premom said i was to ovulate 2 days ago and <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> said yesterday but no positive. Not sure if I’m having an anovulatory cycle.