I'm 18 (hopefully you don't consider that old lol). But if it's one thing I've noticed, age is indeed just a number. I've always thought that when I became 18, I would suddenly become a mature adult, but that's just not true. You're in high school now, but once you start interacting more with older people, you'll realize that many adults still have much maturing to do.
Well anyway, I'm sure getting off topic lol. I know of so many people much younger than me who draw so amazing, I can't help getting jealous even though I shouldn't. We all eventually improve though, so just do things at your own pace