What Causes Lack Of Menstruation Despite Taking Postinor-2?

hi doctors im jane,19 and ive been sexually active and i also have been taking postinor2 like once every month for the past three month now. and i have been very regular i do have a 27/28 menstrual cycle but last month i had my period on the feb 2 and on the 14 i had unprotected sex took postinor 2 the two tablet at once and on the 17 also had an unprotected sex didnt take any pills but im kinda scared dat i maybe pregnant cause dis is the 3rd wk since i took postinor and yet no period and i have been having frequent cramps which last jus few minutes for the past 1wk it normally happens to me when it jus two days to my period but its up to a week now and my breast is also sore which is also normal cuz i do have tender breast wen its two wks or 1wk to my period and it stops wen im close to my period or after my period but its less painful now and ive also noticed dat wen i squeez my nipples really hard a significant amount of clear fluid comes out no dark nipples jus tender breast and my nipples hurt too so the question is is there a possibility that i am pregnant or its jus a delay and if im pregnant will anything happen to me or my baby like an ectopic pregnancy? dis is the 3rd wk since i took postinor and no period im so scared