hii doctor.. I had a unprotected oral sex wid my gf.. we both are vergins .. but I have an doubt that my sperm enters her vagina because of the semens which is explored at her vagina at the time of sex.. we had oral sex on 17th of October .. I gave her unwanted72 pill on 18th of October after 20 hours.... but she not even have withdrawal bleeding till nw . we don't want pregnancy.. what we have to do now.. what are the possibility factors that oppose the withdrawl bleeding