Any cat so anxious that she cannot relax or overreacts to stimuli like the presence of visitors or common household noises should be evaluated by a qualified animal behaviorist. A veterinarian board-certified in animal behavior or a certified applied animal behaviorist will offer advice about behavior modification that can help her cope with her fear and anxiety.
Remember, you are not a failure if you turn to drugs when you cannot get a cat to calm down in other ways. You are a dedicated owner who is doing everything possible to keep your pet from unbearable emotional stress. And your cat may not even need to remain on the medicine indefinitely. Training in behavior modification may allow her to come off a medication over time, or at least take a lower dose, without returning to her pre-drug level of anxiety or fear.