Has your cat been spade? Raging hormones in a teenage cat is just like a teenage person!!! Having her fixed could bring out the lovey kitty you once knew. For her safety and sanity it is the responsible thing to do as a cat owner.
I'm afraid she may not change. Once a cat has grown, in my experience, you can change bad behavior by the squirt gun method, but you can't make them more lovey dovey. One of my cats was very friendly until a 'friend' of my ex obviously did some thing to her she did not like when i was at work. She's never been the same since. Sounds like someone may have done something you'll probably never know about. But just keep doing as you have been. My girl won't go to bed with me, but when i wake up she's there. Maybe after a long time if she's not exposed to whoever freaked her out, she'll become more friendly and trusting.

I raise siamese cats and they can be very moody but they are also very strong willed cats. These are cats that really do require a lot of attention as they get moody and antisocial when left too their own devices when young. You need to keep her out of rooms that you don't want her in. She will get very territorial of that room and will defend it and there is nothing worse than an angry siamese. If you can close off your room and not let her in there to force her to be with the family is really the only solution. We had our male decide he liked our family room and would not even let the females in there, let alone our dogs. We crated him for a couple of days and that straightened him out. We have a large airline carrier that we use for time outs. We put a cat box in there and food and water and no matter how they wail and she will she has to stay until you can pick her up without the hissing. Don't let her out with her first good behavior either. She need to know that her behavior was unexceptable. Also we use a squirt gun for discipline when he or any of the females act out. Who wants a cat that hisses and scratches? The squirt gun acts like another cat peeing on them. In the cat world that is the biggest insult. But it also teaches them that you are the boss. Right now she thinks she is. But know this each cat as in each person has a different personality, She just may be a cat that likes to be a loner. Does she sleep with her litter mate? Spaying her would help a lot too, She may see your purr machine getting all the attention even though it is her fault she does not get attention and be jealous.
Good luck and this should help you to have a more lovable Casey.
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