I don’t know if I have gotten through puberty and if my sins that i commit know are written down

Assalam walaikum, I'm a male 13 years old. (I am really embarrassed to say this) but i have masturbated and i don’t know if it is a sin because I don’t know if I have gotten through puberty, for that sin to count. Please tell me if it counts and can a child do sins until the time of puberty is finished or until puberty starts? On the internet it says puberty starts between 9-14, so i have already started but that is why I wanted to know if the sins count until the end of puberty?