Pregnancy Risk??

So I’ve never had sex with my boyfriend but we do other things(oral and hand stuff) without protection and I’m worried about the possibility of pregnancy when his semen is on me. My periods have always been short(3-4 days) and irregularly timed but lately they are later and later in the month (but otherwise normal) Are chances of pregnancy high with like fluid cross contamination I guess is how would phrase my concern? I don’t have medical insurance so is it worth it to get some type of birth control if we aren’t planning on having intercourse until we are married? Most of the women in my family have gotten pregnant in high school or college so I’m just really paranoid about it.

Any advice is appreciated. 😁