8 days late but negative preg tests--help!!

Katie
Ok ladies I need some advice. I've been off birth control for 4 months now and the hubs and I have decided we'd let nature take its course! I've always been pretty regular with my periods (within a day or two) but this month I'm 8 days late!! So of course after 3 days or so I ran to the store and got a package of pregnancy tests and I took one when I got home...negative. 😑 So I waited another few days and took another first thing in the morning...negative, again! 😑 And last night (a whole 7 days late) it was killing me and I took another test...negative again!?! I haven't been stressed at all, haven't been traveling, etc. I can't figure it out!! 
I told my husband a few weeks ago how I was exhausted ALL THE TIME but no matter how much sleep I got, I didn't feel rested. When I was late, I figured maybe that was a sign I was pregnant but now I can't figure it out! 
I need some advice!