Help!!! He pulled out but...

So last night me and my bf had sex w/o a condom he pulled out but he kinda busted on my thigh not like lower thigh like higher thigh or ig on my butt close to my vagina is it possible I can get prego from tht?!? I really can't be my mom would kill me she still thinks I'm a virgin ugh can any body help me.. should I be worried?!?