ladies help please.

So I am 10 days late. I took a test and it was negative. I'm getting mild cramps and boobs are heavy. 
The <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> app says my next period is in 9 days. But I've missed my period in feb. So what can it be? 
And yes I'm not stressed. So that cannot be. I'm so confused.