Nervous all the time

My boyfriend and i have a pretty healthy sex life considering we see eachother one day a week. Its long distance thing... but anyway i have the mirena iud and have had it for a year now, my boyfriend uses a condom, and also pulls out. But every once in a while i get scared that i am or will get pregnant. I dont want to become pregnant for a while. Because i still want to go to school and my boyfriend is in school. But if anyone has any advice or can help calm nerves that would be great 😊