When does af come?

Kristin • Married 2014👰🏼 miscarriage October 2014🌈baby boy December 2015💙 baby girl due July 2020💕
So I have no idea when af should be coming. One app I have says I was suppose to start today(have not) and this app is saying I start the 16th. Anyone else have this? Not sure when I should consider my af missed