Late period and spotting

My period is now 6 days late and my period has only ever been one day off never this late. This afternoon I went to the bathroom and when I wiped there was some very light pinkish blood so I put a pad on while I laid down to take a nap thinking I was going to start my period. When I went back there wasn't hardly anything on the pad and my period is usually very heavy the first day. I've taken a pregnancy test 2 days ago and it was negative and I don't have any other pregnancy symptoms. Any advice?