Frustrated with opk tracking!!!!

Ugh, first time using opk tests and last!!! Glow told me based on my last period my fertile week so I started using clear blue opk tests. The first couple days nothing then the third day defiantly a second line but not as dark as people have stated it should be! Tested twice in one day same two lines then the next day tested twice and only one line, not even a second faint line!! Should I assume those faint lines were me ovulating then?!