please help! i had sex with my boyfriend on saturday 8 october and he ejaculated inside me. on monday 10 october i took the plan b pill and on the 12th i had brown blood which lasted 4-5 days and it was very little amount. in september my period was on the 14th. i took 3 pregnancy tests and they were all negative. this month i haven't been on my period yet and i don't feel having any period symptoms either and from the day i had sex my uterus is growling like a stomach does when it is hungry. should i be concerned that i might be pregnant? if not pregnancy then what else could be the issue?