Last . was sept 11th-14th. my boyfriend came in me on october 15th. i just started what i think is my period yest. its light n no cramps its not nrml?

Can go ahead: & take a home pregnancy test - so that you know for sure. The main reason for light periods is a change in hormone levels. Causes for what seems to be a light period can include: implantation bleeding in early pregnancy, thyroid problems, eating disorders, excessive exercise, initial periods for a girl, use of an intrauterine device, oral contraceptives & perimenopause.