Hi Memere, I am so sorry that you are in such pain at the moment. I too had a thoracic fusion, at levels T11 & T12. I had my surgery in July 2005, following rupture of these discs causing spinal cord compression. I lost control of bowels and bladder, and experienced numbness in my right leg and genital areas. This was emergency surgery, and I was very lucky not to have been left paralysed fro the chest down. I know exactly the pain you are talking about, it feels as though you are being crushed, you are afraid to breath too deeply. This pain continued for me for a few months, I was so breathless when I saw my spinal surgeon for a review, he sent me stright to re-sus, they were convinced that I had a blood clot on the lung. It turned out to be pluracy.
I know it's really hard to remain positive when you are in dreadful pain, but things will very gradually improve. It took at least eighteen months for my chest to feel any where near to normal.
When you think about what is involved in thoracic surgery, it's not really surprising that you are left feeling awful. If you feel things aren't as they should be, go back to your surgeon, and keep on going back until you get some answers.
I really hope you start to improve soon, take care of yourself.