VFLs and Negative Digital pregnancy tests

So AF was supposed to show up Saturday, and I haven't gotten anything yet. I've taken a digital and a dye test three times, Saturday, Sunday, and Tuesday. All had VFLs and all the digitals were negative. The line was stronger on Sunday, but weaker on Tuesday, does that mean anything? When should the digital detect pregnancy? Am I pregnant or not?! I've had slight cramping all weak, but I can't figure out if it's in my head or not. Also AF has yet to make an appearance.

Saturday

Sunday

Tuesday (today)