I would have to agree with 4horses. If your back pain is so bad that you cannot move some days, it's not stemming just from having DD's. There is bound to be more to it than that. DD's are large but they are not so large that they would cause crippling pain in an otherwise healthy person. I would for sure have another MRI done, if the last one you had was that many years ago, something could have easily been missed and be more evident now. I'm not saying DON'T have the surgery if you really want it, but I don't think it's going to be the magical cure you seem to think it will be. And if it doesn't help your back at all, and the main reason you are doing it is for pain relief, then you may well be out thousands of dollars with no benefit.
"Keep a leg on each side and your mind in the middle"