My period is due on 11/16 but i started spotting on 11/8. My periods are always regular and i am not on any birth control. I took 2 pregnancy tests and they both say negative. The bleeding started off only when i wiped but sometimes its a little more but not much. The most it is is like the last day of a period. i usually have moderate to heavy bleeding on my period and this is nothing like that. I have no cramping however i feel a little more constipated than usual. How long does implantation last and how heavy can it get before it is not considered implantation bleeding. when would a pregnany test show accurate results.