Help!! Opinions please ?

I usually have irregular periods.. 
Currently in 20 days late, and a few days ago I have very light spotting mostly when I wiped after peeing... It was pinkish brownish.. It doesn't feel like a period! I always know when I'm about to start. I took a pregnancy test but it came up as negative. I was reading that it could be implantation bleeding. Should I wait to test again ? Or am I going crazy and I'll have my period soon?