Help i don't know what to do??

Ok so me and my boyfriend have been talking about making that big step into having sex... well i don't know how to ask my mom for the birth control shot, she is always telling me how we can talk about anything. she told me and my bf that if we need it to just ask... yeah there gonna ask questions but they said they would be fine with it. well the other day she said she woulf kick my ass if i lost my virginity... so i have decided to talk to my dad since he knows what i am going through.... what do i say?