The right age to start using birth control

So I'm 15 and I'm not seeing anyone. I didn't think I'd need to be on any sort of birth control until I was older but a lot of my friends have starting using birth control. I'm kind of embarrassed to talk to my mum about it but I just want to know when the right age to start using it is. My oldest sister started taking birth control pills when she was 15 because she had a boyfriend but my other sister started taking them at 19, even though she had a boyfriend by 17. I just really need some advice.