[Latte]

I think how you approach this largely depends on your relationship with your mom and what exactly do you want her to know.

For example, unless you two are exceptionally (and almost unusually) close, I can't imagine you wanting to discuss with her your intention to have sex. Most parents, even the coolest ones who'd totally want you to have contraception, don't actually want any details about your sex life, even if they're helping you access birthcontrol (e.g. providing insurance to pay for it), or even if they know you're pregnant, it's very hard for them to separate you being an adult having sex from the you that is their little baby. Maybe your hoping she'll reassure you and your fears about what having sex is like, but I just truly can't imagine that going well with a parent at all whatsoever. If what you want is to discuss is the act of having sex, I would seek out a friend, therapist, or other trusted person.

As for getting her advice on contraception, I think that this could be ok. You could frame it as sort of "hey mom, I want birth control just in case, because I want to be safe" -- this way you're not going into details about your plans, you're not going to risk the momma bear drive as much, and hopefully she'll give you her support... but ultimately, I'd like to go back to examining what your relationship is and why you want her advice. Do you want her advice? Or do you want her permission? If you want her advice, you could turn to her and just say that the idea of being on contraception makes you feel... something... maybe it makes you feel nervous because of what it means about you becoming an adult... maybe it makes you feel confused because you need an adult you trust to help you weigh the options... maybe you just want someone to tell you that taking contraception is ok no matter what you do.

I just think it's important to question what you want to hear from your mom and why. It'll really help in knowing what aspects of this to divulge to her, and whether you're prepared for all of her possible reactions.