why does it say this

my <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> says period expected on the 18th but my period was already over this time last month ? i know it isn’t accurate always but this is way off from my <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> and flow they’re saying i’m late on my period so now i’m confused. mind you i’m almost 3 months post partum.