chance to become pregnant

okay my boyfriend & I were humping with our clothes on but he pulled out is dick & we continue so i don't know if I could get pregnant that way .... I got cum or per-cum all on my shorts down there so is there a chance for becoming pregnant we are way too young to have a baby we are 16 (me) & 17 (him) so I don't know can someone tell me if I can or not or is that crazy I'm kinda worried & scared