My mom wont let me get a kitten? please help me convince her?

i really really really want a kitten! but my mom keeps saying we'll , not today, we cant afford one right now, you just got a guinea pig, and stufff like that today she said she didnt no about getting a cat so i wrote her a 5 page papper report thing on kittens and she wont read it! i told her i promissed to pay for everything and take care if all by my self aand she keeps saying no! how do i convince her that kittens are cute cuddly and to let me get one??? please help me!!!?