sexual stuff

So i’m 17, and i’ve been with my boyfriend for 4 months now. i’ve never really had any sexual desire to do stuff, like i’d rather just kiss and/or cuddle, and i have no idea why. i’m not on bc or anything. i’ve also never masturbated and have no desire to. i feel bad bc he always wants to do stuff and i never really want to, and i’ve kinda just let him bc i felt bad, but i don’t do much to him and he’s been getting mad about it. does anyone know why i’m like this??? bc i honestly have no clue