Late period..

So my period is pretty regular. I have it 4 to 5 days earlier than the previous months cycle. I am currently 6 days late for my period. I took a test sun and it was neg and took another one today and it was neg so I don’t believe I am pregnant but it’s very weird that my period hasn’t come. I have been having a lot of period cramps and headaches the past week & a half to two weeks on off. Also started having lower back about a week ago so I was pretty convinced af was coming. About a week after my last period I spotted dark looking blood/discharge for about 3 days..wasn’t much more than maybe half a panty liners worth. I think I should test positive by now if I was pregnant right? You think maybe the spotting has thrown my period off or something?