Why is this happening 😩

Okay. So ever since I got my first period when I was 12 my periods came between the 9th & the 12th. Until a few months ago.

April 12th

May 30th

June 29th

July-didn’t get one

August 10th

September 14th

And now Glow is predicting my period is going to come on the 16th.

Could this have something to do with late ovulation? I have been in way more stressful situations than what is going on now & it’s always stayed consistent. I have no idea why this happens. Can someone enlighten me? lol. Thanks.