How can i stop a white fluid from coming out when I think about sexual activity?

I'm really worried.. My boyfriend when touched me even my body parts.. There was a white gooey fluid discharge from my vagina and i didn't feel anything.. When he touched my nipples.. Again i didn't feel anything .. I m 15 nd didn't had intercourse yet .. How can i stop that white fluid from coming out ? Even when i think about sexual activity it starts coming and wets my underwear