What Causes Light Menstrual Cycle?

Ok so I started spotting on the sixth of this month I was supposed to start my period on the 8th - 12 my cycle is around 28-32 days usually I have heavy periods but this time I'm only getting blood she I wipe none on the pad, last and today on the 13th that is still happening but no normal period, last month my period was somewhat heavy with all of clots but not close to heavy like normal I have NEVER had a period light like it is right now but my pregnancy test is negative and I'm only 35 so not sure if I'm starting menopause