How To Prevent Pregnancy?

hi..i had sex with my boyfriend on 3 march .. he ejaculated inside of me but after 2 ou 3 hours i ve taken i pills.Last month i ve got my period on the 9th but its the 11th and i still havent got my period and im really stressed.. maybe that pills havent worked on me .. recently ive taken sesame seeds and cinnamon in case that im really pregnant but im still worried.. i dont wnat a baby..help me please