Am I getting faulty tests?

I posted a few days ago I am not trying to conceive but we had a incident earlier this month and I just happened to be ovulating on, so I'm due for my period tomorow, I've take. pregnancy tests that are all negative until yesterday, I can't seem to get a pic to load from my phone so I'll just explain it, per on the stick and then it will either appear with a line like this | to mean pregnant or nothing will appear and I'm not, well the line was barely there but it looked like -- this. Then today I took another test and it was a blurry line but it was defiantly there, what's going on here?