15 and Pullout. Pregnant?

Im 15. I lost my virginty 2 weeks ago to my boyfried who was 16 at he time, now 17. we do it on a regular basis because its hard to see eachother as i live in a city and he lives in a town which is a 40minute drive away. We do use condoms but sometimes we dont even though we have them and instead we use the pullout method. Which we both realise is wrong. He pulls out a good 15 seconds before he finishes after telling me that he is about to. What are my chances of being pregnant?