It is not pointless for you to speak. But you seem to be talking in circles. You contradict yourself over and over. Did you expect this declaw/no spay thing to go over well here?
All this declaw stuff is about your mom not wanting the cat to have claws. You say you know it isn't good, but you want the cat so badly you'll do it anyway. You have talked yourself into believing it is no big deal. What if your mom didn't want the cat to run around, would you remove a leg? Or if she didn't want it to chew things? Would you pull its teeth? Yes, my points are exaggerated, but they are one in the same. And you know that spaying and neutering is very healthy for an animal- we didn't have to tell you that.

You say you can't move out financially with the animals. But, why not prioritize and save money, work on an education and a career so you can move on your own and be a self-sufficient adult. Then you can give a good home to the animals.

I seriously think you would do right by any animal. I can see that you love them alot. I just think you are letting your desire for a kitten right now overwhelm what you know to be right. When you can care for the cat YOUR WAY, I think it will be awesome. But your mom's way is wrong. Soft paws aren't that expensive. If you can't affored them, what will you do if the kitten gets ill and needs expensive veterinary care?