Take benzos with caution. Don't double the dosage. Use them only when you need them. Doc's often overdo the dosage or escalate to a really dangerous kind.
If you have to, go off slowly. Begin with your normal dosage. Maybe two or three days later (depending on you) cut it in half if you can. Then go progressively down to 0 according to your body. If you get headaches or nervousness, recognize the withdrawal symptoms and take the dosage your down to. (If it's down to a half tablet, take another half.) Use a razor blade to make the cut even to a third of a tablet if you have to.
I am not a doctor. (I have to say that.) Believe me I seen it myself because I take them. But I know I am not dependent on them except for what they are for: panic attacks, anxiety. They will depress you at times. Know that.
Buspar is absolutely useless for something like PTSD. It's for GAD (generalized anxiety disorder) and barely does the job for that.
Believe it or not, studies show that breathing deeply (as in meditation) and emptying your mind can often have the same effect as xanax. Doesn't always work but it has at times for me.