Where is my AF??? Need advice please.

Brandy • Married. I have an 11 yr old. Hubby no kids yet.
Keep having to click on "my period is late"... App recalculated 17 times. I showed postive for ovulation Feb. 25. thru March 8th. Previous AFs were Jan. 6-11 and Jan. 27-March 3.
Negative pregnancy test since 3/10. Never been off or late for this long. 
Jan