First response faint line but clear blue NOT PREGNANT
so I last had sex September 17 which according to my period app would have been my fertile/ovulation week. I am now 13 days late. I took a first response test and it looks as if there is a faint faint line. But is it a positive line or an evap line? i can't tell. I also took a clear blue digital tonight and it came back not pregnant. I'm hoping it's not a false positive (the first response test) but I'm worried it's just an evap line. I looked at the first response test after took it and it said negative (unless the line was just so faint I didn't even notice it) then saw it in the trash can after a little while and it looked as if there was a line. Obviously the window was no longer white when I saw the test the second time. It was yellow. So the line was visible to me against the yellow background. What do you guys think? Help!