Ovulation

Enerica
Hi lady's 😃✌️
Am a little confuse on how this all situacion about getting pregnant works. 
My period is most of the times on the same day, last April my period came on the 20th and it also came on the 20th on May . So when I put this info on the tracker it tells me that my opportunity of getting pregnant is during this week , but my ovulation test tells me am not. So how does it work ? So if am ovulating I get pregnant or I get pregnant before I ovulate ? Help!!!!!!!