what are the chances of getting pregnant from pre-cum?

[Amairani]

okay well i had sex with my boyfriend and we did it without a condom. we always use protection but this time it just happened. we did it two times like that in the same day. the first time we did it he pulled out and then he went to go clean up. then i did oral on him and he came inside my mouth and i kept on going. but i cant remember if he went to clean up afterwards since we werent planning on doing it again. but then he was leaving already and afterwards we were just messing and it happened again. and he pulled out. he is sure he didnt ejaculate in me because i saw when he did and it wasnt inside of me, it was by my belly button. i want to know what are the chances of getting pregnant and want to know if, even though he cleaned himself real good, could there still have been sperm inside his penis? please give me honest answers and real answers please. something said by a doctor like facts or something would be great. thanks.