is this app normally correct

martina • 22, one 4 year old boy, one 2 year old girl and expecting my third in july
I'm just wondering if glow is normally on track of things.. because i have like 4 apps to track my fertility and 3 of them all say i was fertile last week and my ovulation date was on the 19th.. but then the one i used since last July is telling me I'm ovulating tomorrow. someone help please!