Advice needed tmi

My af was due 7th but no show. I could feel slight cramps for a few days leading upto this but not as bad as i usually get them. Started what i thought was af on the 15th(6 days late) but started of browny red then pink and now back to darn red /brown and has almost stopped. (no were near full or half full pads) with barely any cramps. I have 28-30 day cycles. I have tested negative on the 7th (day af was due)... Has this happened to anyone else? Has anyone got an idea what is happening. Why has my period only last 2-3 days (usually 5-7) and very light & also 6 days late Thank you x