birth control talk and i got a not so good respond! what should i do

so were talking about all my friends that are pregnant and my 10 year old brother is in the back seat, he goes dont you just get pregnant (as in like your friends are so young why would they get pregnant) we say what? he goes like dont you just do it we said what do you mean he goes well mom never wanted to get married how did she have us.. we explain she was in a relationship but they were not good people and marriage didn't happen but she did want marriage at some point.. then later on with the friends pregnant talk my brother goes but why isn't there medicine or something inside of u to avoid pregnancy we goes yes of course there is

actually talk!

i say yes there one that goes inside your arm i said mom can i get that SHE goes WTF FOR! i said maybe because i dont want kids! SHE goes well you shouldn't be having SEX! i said i saw a picture that said it doesn't matter if ur 18 in a Hispanic home it doesn't change anything joking around she goes u damn right lol

so I'm 17 going into college in like 2 weeks no kids and i would like to at some point have sex i been with my boyfriend for 3 years now in Dec and i would like to have sex but i am terrified of getting pregnant! what should i do?? should i speak to my doctor n see what are my options behind moms back?? am i wrong for asking my mom??