so i had my period on December 19,2012 and i had sex with a friend on that same day in the shower and on the 20th too.. then me and my boyfriend got back together and had sex January 2, 2013,, went to my country the 3rd and came back the 11th, me and my boyfriend continued to have sex up till 20th of January 2013, also i had light bleeding on January 19 and then no blood . got brownish little spotting on 21st.. I think I am pregnant so i would like to know the date i conceived and who the possible father is, my friend or my boyfriend.. thank you