6 day late cramping no period, im confused ?

Okay so I'm 6 days late, my period  is  like clock work except I was about a month late a few months back which was odd but now I'm late again, I get werid spazams in my uterus every once in a while Iv been cramping some but no blood I took 2 test one was negative the other was what I thought was negotive i can back a little after an it looks like this it looks like a dye run, but any thoughts ?