If some colleges and universities are more open and allow college students to keep pets, you need to negotiate with your roommates and get permission to prevent your roommates from being allergic to cat hair. The dormitory is a small public place.
My suggestion is not to keep small animals in the dormitory. In fact, the personal space in general university dormitories is not that big, let alone the balcony. Some university dorms don't even have balconies.
To say the least, there are actually many cats and dogs in colleges and universities, and some colleges and universities also have geese and hedgehogs. If you really like small animals, why not try "body double literature" on them?