Confused??

Tj <3 • 23// England// 26-07-18 👼🏻18-09-18 👼🏻4-1-19👼🏻 Elsie 💕 07/03/2020 19-8-22 👼🏻 Baby boy 💙 - due may

<a href="https://play.google.com/store/apps/details?id=com.glow.android">Glow app</a> says I’m due for period today ovia says I was due 3 days ago, both have the same data which is more reliable?