Donna you obviously love your cat and it's brilliant you consider her so much regarding the move to your dream apartment. Not wishing to fall out with the previous post (Hi, how are you Schutzengel - didn't we talk about cocker spaniels and their role in life or am I having a senior moment?) there are a few considerations you may not have thought of. How old is your kitty, is she a hunter, how big is the balcony, how long will she be alone, how long was she left alone before and was going out 'to play ' a big part of her life?.Answer a few of these question and depending on the answers your kitty may well live very happily in a flat with a PERFECTLY SECURE balcony -she also may like to get used to a harness and go play in the countryside with you on a regular basis. Talk to a professional to get info on introducing this because if done wrongly you don't usually get too many second chances with cats!!!) but if successful it's brilliant. Animals are very adaptable and providing they are loved and cared for appear to adjust very well to changes. Obviously you would provide her with a secure environment (containing lots of stimuli and different heights for her to use- important with cats - less so with single cats but nevertheless important) and maybe cat friendly herbs plus lots of love - so I would say, follow your insticts and keep us informed - good luck