This app man

So my calendar originally said my period is due the 18th and I ovulated a week ago and I keep getting positive OPKs and I log them and every fucking time it moves my period further away. Like who the hell codes this. It’s very annoying because one day it’ll say my period is due a certain day and then the next day I come in here it’s a completely different day my period is due. What the fuck is all I have to say about this. What the actual fuck.