I have three cats, all from rescue centres. I've had one years. He is no trouble.
The other two are black and white brother and sister from the same litter. They were kittens (12 weeks) when I got them. They have always been nervy and highly strung. They both enjoyed going outside.
Two and a half years ago I moved from a house to an apartment. Cat 1 adapted without any problems. He goes out and miaows loudly when he wants to go in and then decides he wants to stay out so typical cat really :)
My 'kittens', who are actually nearly 5, just haven't adapted.
Girl cat was out almost immediately hunting everything 
but she often won't come in. Last night she wouldn't come in and this morning she wouldn't. She stands at the door of the apartment and she's obviously cold and wet and hungry. Boy cat is the same. But it took him ages to work up the courage to go outside. It's as if they look into the apartment building and because it's not 'their' home they are scared to come in. Sometimes the girl will be out for two days, the boy for four to five, with nothing to eat in this time. I try to coax them but they won't.
In the apartment they run away from me and they just seem to be stressed and dislike me.
I've tried feliway, it hasn't helped really.
Problem is, who would want them? Rescue centres are overcrowded and they aren't loving people cats.
Should I assume they are best off with me? They just seem so unhappy? 