Week old pregnancy test.

I took a pregnancy almost a week ago (Monday afternoon) the test results came back negative. I checked it again this morning because it was still in the box and there is a faint line stating it's positive. Could this mean I'm pregnant? I'm on the depo shot. We had sex 3 days after I go it and he never pulled out. We had sex a week before i was on my period. He never pulled out. I've been having all the cravings and symptoms. Anyone know if I am or not?