Bluey...I have to agree with most everyone on this post. Outside can be a scary place for a cat and if at all possible I would encourage you to try to keep her inside. She is still relatively young so maybe the change-over won't be as hard as if you had waited til she was older and "set in her ways." Both of my cats are inside only cats and believe me there is much less to worry about. Some people here at Pet Talk have created outside enclosures for their cats but unfortunately that would be a little hard to do for you off a balcony. By the way, I love the name Mushroom!