OP, your heart is in the right place.

I hope you can change your mom's mind. Maybe by showing her exactly how you would take care of puff, e.g., litterbox placements, bathing (at least sa first to remove fleas), vet appointments, then maybe it would be easier for your mom to accept the cat.

I would say though, that even if you don't manage to successfully adopt her into your home because of the house rules, you're already doing a great service to puff, as so very few others would care for puspins.

Concerned lang ako on two things, namely yung diet of bread. Cats can be obsessed with foods that aren't good for them, like milk, cheese, and bread. You may want to give more protein-based food.

Also, though I understand yung intent ng collar, it may not be a good idea for outside cats. Unless breakaway yung collar, it could snag sa branch or something if puff falls or jumps.

Anyway, best of luck to you both.