I want to get a cat! But my parents will not let me!?

I have wanted a cat for quite some time, but only recently became vocal on the subject. I get A's and B's in school and am very responsible! I have even been taking care of the family dog all most all by myself! I do the dishes without being asked, I take out the trash, and I do things like this to show my responsibility in the household. I am 14 years old and we live in a very small town (population is something like 230) My Dad has said I can not get a cat until the Dog is dead..or until I move out. I have a very large fear of growing up and leaving the house, mixed with abandonment issues. My mom thinks that she will end up taking care of the cat because she did with that with the Dog when we got him and she only worked part-time so when we were at school she let him out and fed him and what not. I like my dog, but he dosent like me. I really just want a pet who will be there for me, who will be as happy to see me when I get home from school like my dog is when my mom gets home from work... Any suggestions are really appreciated! My mom is also afraid that the cat will claw up stuff when we are gone and what not... My mom and dad said that money is NOT an issue in getting a cat.. They both like cats and have gotten them before... It just seems so unfair Thanks :)