I personally keep my kitties indoors all the time. The area where I live in just isn't safe for kitties to be roaming around outside. I think depending on where you live an indoor/outdoor cat is fine as long as you are able to be outside with your cat to make sure he's safe. However if you are planning on keeping your cat outside 100% of the time, then maybe owning a cat isn't right for you. Maybe you can talk to your mom about getting her on medication. I'm allergic to my cats but I still have them anyways. I take medicine and use an inhalor once a day and I'm fine.