SEX SCARE

Please somebody help me out. I want to know, how deep a penetration do u need to break your hymen? My boyfriend and I were having touching intimately and he put his penis in my vagina but he didn't go all the way deep, he did some shallow thrusting. Did he break the hymen?  How far up is the hymen? his penis was only half way in and he might have precummed too am i safe ? cause i don't think a person can get pregnant without full penetration please educate me if i'm wrong