How to become an actress?

Hi everyone, iam 13 and i'm extremely serious about acting, i have tooken extra curriculum in school for acting, i have been alongside year 10's and 11's in the school pantomime and summer play. i have researched acting but there are tons of things out there that just put you down and say that you have no chance but there are manny actors and actresses that start from a Young age right? so please help me with anything you know and what i should do by the way I'd like to act on tv not THEATRE(although, theatre is what i do now) thank you so much, i know i am little girl with a big dream but it could be true