worried

so normally my periods run on 27 day cycle but for the past two months they have been on the 24 day cycle . with that being said yesterday was the day my 24 day cycle would of been no period ,no bleeding and no spotting . have noticed this morning tho I have cramping in my right side . I did take a test yesterday which was negative... and one else experience this ? I should also meation I have been off depo since January 2016 and have had periods every month since