how do i (16) convice my parents to adopt a cat

TLDR: literally just the title! but more info below for context etc

we already have a dog who i love to bits, but ever since i was 7 years old i've dreamed of having a cat. my dad has already admitted to being a cat person and said that he would be okay with it, but that he needs to talk to my mum.

i completely respect that! i sent them both some info etc on new cats bonding with dogs, how to introduce a cat into your home, etc, and i've made promises to do ALL the work! i already walk our dog when i can and feed him etc, and i am generally quite a responsible person.

my mum's just being really unresponsive. if she doesn't want one, that's fine, i get it, but she's just not discussing it with me! i've told her i can pay for everything with my savings and that riley (the cat i've found on blue cross adoption) will be completely my responsibility, but she is yet to come round.

any advice on getting her to come around, or just letting her know i really care about this and am willing to do all the work?

thank you xxx