I have a question

I just had amazing sex. Amazing. It was the first time my boyfriend and I did it without a condom. Wow it was so good the feeling was indescribable. I have the mirena iud and my boyfriend pulled out at least 10 seconds before he finished. I know the worry about precum but he also went to the bathroom right before we had sex. What is the possibility of me getting pregnant. Im just curious my boyfriend is worried.