Should I tell her or .....**update

Soooooo today I was riding in the car with my grandma (she more like a mom since she's been the female role model in my life) and randomly she just say "when you start having sex I want me to tell me" I'm 14 so I was like "......no" and she says I want you to tell me so I can get you on birth control and get you into a gynecologist , and I tell her I don't want to tell her when I do cause she'll be ashamed and give me the death glare and she said probably but it's important. Well any way I AM sexually active like I receive head from my boyfriend and he fingers me and I give him handjobs and head we've agreed to wait until I'm in highschool to have sex (he's already in highschool, he's 9th grade and I'm 8th grade ) but should I tell my grandma to get on birth control or wait till I have actual sex ? And please don't be mean cause of my age I still focus in school and have a plan for my future.

Edit : all of y'all have told me I need to tell her and thank you for your opinions but how do I tell her ?? I already know she won't ever look at me the same way if I tell her 😔 she'll be disappointed and ashamed, how do I tell her?