Thank you so much for your service! When I read stories like yours I am filled with gratitude.
It sounds like you have a legitimate need for pain management and no advice you'll find on the internet will substitute for the care of a doctor familiar with your particular case and all the treatment options available.
However, I can suggest something for you to bring up with your doctor. A friend of mine also had a back injury from a car accident and found herself addicted to oxycontin. That in and of itself is not necessarily bad for someone in real pain, but the problem was she would take more and more and her prescriptions would run out before they were supposed to. She had trouble differentiating when she was taking pills for pain versus taking pills to "feel good."
The solution that her doctor gave her was a fentanyl patch. Fentanyl is a powerful painkiller and it comes in a patch which you stick to your skin. It releases over a 72-hour period. So instead of taking pills, she would just put on one patch and know that was the correct level of medication. Every couple of days she would change it. No more escalating cravings! Just food for thought. You should of course ask your doctor.