pregnancy scare

i researched this but i really need to be safe, i am 16f and me and my boyfriend do the pull out method - i am on cerelle (contraception pill) however when i had intercourse today my boyfriend said he might have left a small amount of precum inside before he pulled out. As i did research i know that the chances are extremely low but i wanted to make sure im not pregnant because its a specific situation and i am looking for some reassurance