Help!

I am 2 days late for my period and let me tell you I have never ever been late for a period in my life. I've been using this app for the last 2 and a half years and it has been spot on with my period since. I took 2 pregnancy tests today; the first one was positive but with a faint line, the second one was negative. What does this mean does anyone know? I don't want to get myself all excited for something that's not real. Please help! Has anyone every experienced this?