Why does glow say my next period is in 14 days?

↞ηιcσℓε♡↠ • 15 very long years of ttc! Not giving up though!!
I was supposed to start on the 5th I started on the 4th it was 2 days then some spotting after. Now glow says my next period is in 14 days. Even if I had a short period it's around when I should have started so why would I get another one so soon?