Suggest Medication To Avoid Pregnancy After Unprotected Sex

Hello. I am 20 years old and I had intercourse on the day i assumed my period had ended. We did use a condom but shamelessly speaking, we had hard sex and on ejaculation he did pull out but sometimes it was not on time. I had a little bleeding incident during intercourse but not quite sure if it was just the hymen breaking or my period continuing a little. It has only been 48 hrs but i get this doubt in my head that i might have completed the conception phase although the chances are really low. Also, after sex, my urine has been unusually yellow and i have no idea if it is supposed to be that way for everyone after sex or for someone who has just conceived. I want to avoid implantation at all cost but only naturally. What can i do or eat in order to avoid implantation? Also, is it possible for me to become pregnant with all the above information provided, considering the fact that my periods are usually regular and once in four months irregular? Also, only after knowing the early pregnancy symptoms, i have started to crave for food but again it might be because i am assuming there might be chances of me being pregnant and i already know the symptoms. Please help.