I Want Mis Quince!

I wan`t to have my 15, but my parents think I don`t deserve one. (and they say it`s too much money) I get good grades in school, I don`t get in trouble at school but I`m sorta lazy at home (but who isnt? lol) How do you think I should convince them to let me have my party? And if having my 15 isn`t possible, then I`ll try for my Sweet 16 instead. I really want to have my quince becasue all my friends have theirs and I think there is a lot of meaning to it; you are no longer a kid, you`re becoming a woman. PLEASE HELP!