condoms always breaking

yesterday I was with my boyfriend and the condom broke 3 times. I'm extremely scared to get pregnant cause I'm only 15 and my parents don't know I'm sexually active. I'm not sure if the condoms are too small? he said they would always break when he was with his last girlfriend. I don't know if his penis is really big or not because I have nothing to compare it to. also, he's not circumsized.