Irregular period

Okay so I am coming off depo and my periods have been irregular for 9 months, seeing as I quit it in January. I haven't had a period since July 26 and I just started it today. I entered it I'm my Glow log and now it says my next period is in 80 days... Wtf? I really dislike how glow doesn't give you an option to not have a period one month. Its kind of common to miss if you have PCOS or if you are weaning off birth control.