Birth control

I’m 16 n I’ve had sex before a handful of times (pls no judgment I just need answers) and I want to go on birth control to be safer but I’d still use a condom. I don’t want to go with my mom bcuz it’s awkward n I don’t tell her I’m sexually active with my bf. And I was planing on going to a clinic with my sister who’s 19 n she’s getting on it too but i was wondering if I need a parent/guardian to go with me to get it. I was also wondering which would be better the pill or the shot bcuz I’m a very forgetful person so I’d forget to take the pill and the shot would be more discrete. Also my grandma has said that she’d put me on birth control if I asked just to b safe than sorry but idk if she’d tell my mom n I feel like it would be awkward. Advice pls?