Need opinions!!

Okay af was due today. I have a regular 28 day cycle and it comes like clock work every month. The day before I will cramp and that's it. It usually starts out very light and as the day progresses it gets darker and the next day gets heavier.. Yesterday afternoon I started spotting. I just thought okay shark week is coming early this month. No biggie.. But today it's exactly the same! No heavier no darker. This is unusual for me.. I keep getting bfn every time I test.. Can someone please offer their opinion?