Who would actually agree to be my publisher?

I mean like be my actual publisher

okay but i don't think i'm even that good and my parents wouldn't approve probably

Of course you're good! I can almost guarentee that if あなた showed your parents your お気に入り song, and 発言しました that あなた might want to get it published, they would say sure! If not, ask if あなた can when you're 13, または maybe 16!