Late but not pregnant?

So Glow and P Tracker say I’m 5 days late, Flo says 3 days late, and Ovia says 4. All my apps are different. But Friday I was in the hospital for dehydration and my electrolytes were all off and they did a pregnancy test per standard protocol and it was negative.

Where is my period!? Idk what to do. Has this happened to anyone? My periods are irregular, but the latest I’ve ever been was 3 days late and that was only once.