I cannot believe it, this is 2013 , all kinds of sex education, birth control, etc. available and you are using pre- historic methodology! Hopefully you got away with it as the world does not need any more people with no sense of responsibility!
It is possible to get pregnant 7 days before your period, because this is when most women ovulate. The pre-cum which comes before ejaculation sometimes has sperms which are responsible for fertilization.
anything is possible however there are other birth control method out here you need to Look into that and pregnancy is not the only thing you should be worried about there are STD'S you need to protect yourself
Your boyfriend could have pre cum in his urethra before he ever drops his pants.... pre cum has sperm in it.... so he doesnt need to ejaculate inside you to get you pregnant. Let me guess.... He probably told you to jump around on your heels in circles to make sure you dont get pregnant too, right?? Please educate yourself.