7 days late & 7 bfn..

I am 7 days late today. I have taken 6 line tests & 1 digital & all were negative. Has anyone experienced still coming up pregnant with that many tests negative? I usually don't stress it but I started a diet plan with my doctor and it's 1000 calories a day and on medicine to help curve my appetite. I'm concerned because that's not ideal for a pregnant mommy. Opinions? Am I over thinking?