spotting period still late

my cycle should have started may 13, 2012 but it did not. I thought I started my period. on the 24 of may it started out medium flow then turn too brown pink red spotting .when the 25 of may hit I only saw spotting when.I wiped.the blood does not smell at all no cramping are anything my pregnancy test still saying negative still spotting it is the 29 of may could I be.pregnant????