I want a cat but?

Hello, I'm also a great fan of cats, and used to have eight at home, now I have four. I have major advice for you, are you prepared for a cat?
Yes I understand cats are not as much work as dogs, but they have low tolerance levels, and have a wide range of personality. What breed are you looking at? If you have a breed in mind, have you thought of the responsibilities you need to take on? Long furred cat breeds need more grooming attention, as well as expensive vet grooming sessions. If their fur is not payed attention to, it can cause severe matting of the fur, shedding, and a nice comfy home for a flea to rest in. Then there comes smaller cat breeds, have you thought about different breeds that have more medical problems and neeed more regular vet check ups than others? Have you thought about skin cancers with hairless cats? What about spaying, neutering and pellets? It costs so much to own let alone a single cat, so I'd say, think about all of this first, are you sure you are up to own a cat?
If you and your parents have already discussed the high amount of responsibilities, maybe take a look at being patient. It's impossible to get a cat if the landlord is simply saying no, and so are your parents. It sucks that you aren't allowed a cat, as they are great companions. I would say, do not push it anymore as you could ruin your chances. But if you feel up to it, then here are some things you could ask.

Maybe talk to the landlord professionally and talk to them about the amount of stray cats or injured cats that are put down every day, and how you want to adopt. If you don't want to adopt, maybe tell them you are great at looking after pets, and numerous landlords who have said no to pets, agreed. Say you need a companion to keep you company in the day, and that if any mess is made, you will clean it up. Don't fight with the landlord if they say your cat needs to be an outdoors cat or if your cats litter box stays outside, it is their house in the first place, so simply nod and say you will do anything to make things work. Say you will have the cat spayed and neutered, and say that you can keep a cat for a week, and the landlord can check up on the house on the last day to see if you kept your promise, then if the house is fine, you can keep the cat. The last choice is up to your parents, ask if you can move to a more affordable house, where they do allow pets, you may be surprised by what your parents say.
If the possibilities seem endless, and everything I've said and you've thought of leads to a dead end, then you need to accept that no means no. Maybe in the future, you can get a cat, but in the meantime, you may have to be patient. Good luck with persuading a landlord and grumpy parents!