How hard is it to actually get pregnant with the pull out method?

I’m 17 years old and recently me and my boyfriend have been using the pull out method (I know it’s not actually a method but you know) and I’m always scared that I might be pregnant. We’ve been doing it for a while and it’s been going fine so far so good. We’re going to get condoms now obviously bc it’s stressful. But how hard is it to actually conceive?