Spod, my dh takes gabapentin, 1800mg in total per day. The upper limit is 2400mg per day. He's been told if the gabapentin doesn't do too much to help his chronic pain, he can try pregablin instead.
Hard to say how effective it is as he is also on shedloads of other painkillers and things (liquid morphine, fentanyl, amitriptyline, and dear old paracetomol for good measure). He has been upping the gabapentin of late though (at doc's advice, not in random fashion!) as the opiate-based drugs don't seem to be helping too much. Seems to be helping a little.
This comment is probably completely irrelevant to you, as dh has fibromyalgia, completely different from your condition, but he's really noticed some benefit from acupuncture. Don't know if you've given it a try? Obviously not as a replacement for medication, but to work alongside it.