I need some advice

I feel like I'm going crazy. I've never been a day late on my period in my entire life ever until I was pregnant. So, I am 4 days late and my tests are consistently either very faint lines or what I would believe to be negative so I'm getting mixed results, here is the one I took this morning.

Which looks like a faint line to me. Call me crazy, but my problem is that they don't get darker every day. I have cramping all the usual symptoms have even felt nauseous for days and yet no period nothing. I'm really confused as to what is going on.