Confused?

Can someone please explain this to me? 
So I had my period on May 9th-May 14th 2 days after I stopped my period. 
Well the <a href="https://play.google.com/store/apps/details?id=com.glow.android">Glow app</a> lets me know my percentage of getting pregnant. Okay? Well yesterday was 27% and today is 33%. Well when I took my ovulation test is says its low?
I'm really confused can someone help me out?