I spotting on jan 9 i was on and off my period on the 10 and now today the 11 i have light pink with brown. what can be wrong. i go 4 days every month . i had sex on december 17 no protection. my period was suppose to come on the 3 of jan ?

Hard to guess: For fertile women who are having sex... it can be hard to tell if a woman is pregnant because some of the symptoms seen in early pregnancy can also happen in non-pregnant women. A home urine pregnancy test gives a accurate result. One can test about 3 weeks after sex (3 weeks after when conception might have occurred), 1 week after missing a period, or 1 week after starting a "weird" period.