Opk as a pregnancy test

Melinda • Had 4 miscarriages in 2015 and had our rainbow baby December 2016
I've often seen people ask if you could use a opk as a pregnancy test so I wanted to see what would happen. I'm currently 7 weeks 2 days. I just took this opk at 10:30am using mid morning pee and it took all the color from the control line. Not  sure how accurate it is for a early pregnancy test but it's working this late in the pregnancy.