Faint negative??

Hey y’all, my bf and I haven been down for having a baby for a while and are far from careful and never had any luck. He also thinks he is infertile. On my flo app I’m 2 days late, (that’s my more accurate app) on this app I’m supposed to start today or tomorrow. So I took a test because it can’t hurt and I assume the results would be accurate but i got a faint negative? Im assuming I’m not pregnant but why is the line so light? I’ve never had a negative show up like this and I peed first thing when I woke up so it was not diluted.