Mom said I can’t have BC help??

I just want someone to be there for me and give me advice or at least guide me. I simply wanna be responsible and safe but my mom keeps telling me I should wait a little longer. I should wait till after university. But I’m 18 not that it matters but I think I’m old enough. But we literally had the most awkward conversation and she was mad I was asking for birth controls. Unfortunately I only trust the internet or the strangers of internet to help me. Idk what to do. I’d love to get on the pill but she would find out and be disappointed but the injection will make me irregular and gain weight so idk? Help please