Anyone who's been regular for years randomly become irregular?

Raeanna • 25 yrs old, full time student & full time mommy
So I've been regular for years but only tracking my period on an app since 2012(not this one). Cycles average 27/28 days and periods about 4.
​Well period came about 2 weeks late in May and a week in June. Instead of a bunch of red both times it was mostly brown except for when I started and spotted. May was about 4 days and June only 1. Both times very light. Now it's July and I was suppose to start the 5th. 
​My last 2 cycles on another app show 34 and 39. Going on 32 according to it for this one. The lighter periods I don't mind although I've never been too heavy but it sucks during summer to not know when you may start.
​I haven't been stressed to cause the delays. Plan to go to my obgyn in 2 weeks just to make sure nothing serious is going on.
​Just wondering if anyone else had this happen or know someone?