I had unprotected sex and had no birth control pills or what not. 2 weeks later I got my period but it was different it was shorter for like 2 days and then the 3rd day it was just light/brownish color. I dont know if I am pregnant.Can anyone tell me what are the chances of me being pregnant and I took the test a week after i had unprotected sex and said negative. and then 2 days after and it still said negative.I waited a total of 12 days to see if i am pregnant but ended up negative. I have back pains and have been feeling tired and light headed lately. SOMEONE PLEASE LET ME KNOW! and when should i take another test to be more accurate?