P.o method

Im surprised i still have not got pregnant. I lost my virginity when i was about to turn (16) and ever since me and my boyfriend have been having un protected sex pull out method and yes i know its not a good idea but i still have not got pregnant and i am surprised its been 8 months already and people say it can get you pregnant this and that but i just think it depends on the guy if he makes it out on time and my boyfriend is always on time.