Had a very light 6 day period breasts are larger not sore using the toilet more feeling sick all the time tired alit, done test says no?

Not sure of reason: The main reason for light periods is a change in hormone levels. Causes for what seems to be a light period can include: thyroid problems, eating disorders, excessive exercise, initial periods for a girl, use of an intrauterine device, oral contraceptives, perimenopause ; implantation bleeding in early pregnancy which rarely occurs.