It sounds as though you and your vet are working hard to solve the problem, but not making much headway. It is clearly not acceptable that she causes injury to your or others. Cat bites and scratches can be dangerous - not so much the injury itself as the risk for infection. Aggressive cats can cause serious injury to young children and elderly people.
Trying to understand the cause of the aggression is important; addressing that underlying cause is the only way you will solve the problem. Is there a trigger? Is it territorial, or other inter-cat aggression? Is is fear?
I think setting your expectations is important at this stage. For example, some reasonable goals and expectations might be:
- She will probably never be a cat that will sit happily on your lap. But can you get her to sit peacefully on the same piece of furniture with you?
- Can you safely touch her? Not to pet or brush her if she doesn't like that, but just to be able to do the basic things you might need to do such as get her in carrier, or take her into another room.
- Can you get her to live with the other cat without causing him injury? She doesn't have to like him.
- She will never like strangers, and there is probably little you can do to change this. Can you get into a routine to shut her in another room such as a bedroom whenever you have visitors?
Now you can't expect to achieve these things overnight, but if these or other basic expectations cannot be met then you really have to consider other options.
Honestly I think there is little that a veterinary behaviorist will be able to add that your vet already hasn't tried - although it is always a good idea to get another opinion in these cases.
I would strongly consider trying to rehome her. It sounds as though she is a cat that would do best as an only cat. Cats are solitary creatures. We humans like to get cats in pairs, and usually they will adapt just fine to this, but some will not. You can talk to your local shelters or rescue groups to see if they have any suggestions for rehoming.
