trouble with period times

Breean • Mama to Delilah Mae Dexter Kash and Declan Grey 💖
So last month I had my period from the 8th until the 14th. And then it said I ovulated on the 29th! And then in January it said my period isn't supposed to start until the 12th what the heck!? Also I downloaded and app "estimate your due date" and if I got pregnant it would be September 14th BUT that app said I would have ovulated December 22nd I am so confused !😭