About all I can offer is swelling and inflammation from your past surgeries could still be figuring into this. You could use a CT scan or MRI to see if you still have some nerve root entrapment (since your spinal cord, albeit injured, was not severed). The physician looking after you on this issue should perhaps try steroid shots or pills to perhaps bring down any lingering swelling, if it shows up on the scan. Your muscles CAN be strengthened even if they are not responding to signals to pull tight and release, which the physical therapy people shoud be able to help you with this. Other than that, the only other comfort I can offer is thank heavens you survived the injury, even tho your quality of life has decidedly been affected negatively. Keep working at your recovery, get a second opinion, get a scan, ask for anti-inflammatories, shots, whatever it takes to get you in a little better shape than you're in.
I will tell you this, neuropathy is a strange thing, I have it from a bad back, which numbness and swelling pain was worsened by chemo-induced neuropathy, and after a year, most of my feeling has returned from the chemo, and I take Lyrica (cousin to Neurontin). I basically stayed off my feet on hard surfaces as much as possible, altho i continued to walk in my yard or on softer surfaces like ground, propping them up on a pillow whilst stretched out and relaxing, and massaged my feet, pushing hard on the soles all over. I made myself drink extra water.
As for you walking slow, all I can tell you is I'm 60 years old, and I walk slow now, whereas just ten years ago I was studying ju-jitsu, VERY frustrating, but I suppose with age this can be expected, so I sort of fit right in with my aging community. But YOU, you may not be in that realm yet, but I can tell you that nobody really notices how slow you go... my husband is as strong as an ox and yet he has ALWAYS walked very slowly and deliberately, just a habit. So, not to worry on the slow thing, and if your back really does finally improve, and if you can get those muscles to tighten up better (I wonder if they can apply electricity or something), maybe your speed will pick up. I really do not know the solutions, I'm just trying to comfort you and offer sympathy since I have similar problems with my back and feet.
I have been 21/2 years after my injury, I had multiple levels if injury due to an infection trying to eat my spinal cord and column, laminectomies 3-5 vertebrae sections from up and down the spinal column cervical Thoracic and lumbar later a cervical fission c3-4, & c4-5. Initially paralyzed from the neck down All that to say I'm still getting better with marked improvement. from wheel chair to starting to walk 8 mths ( not pretty but walking) walking better now with more strength though still not perfect gate. So many things have come back. I IC & still struggle with bladder a few drips but mostly I have trouble releasing, sometimes can never a big full stream but sensation is getting better so Hope but I'm not back to peeing on my own yet.
Here's more hope for you Some guys that have been through this said 3-5 years they kept improving until now no on could tell they ever had an issue Keep being thankful to God for what you have and keep asking for more... never give up never give in, keep working and pressing. by the time this posts you may have already surpassed where you were before the accident, but if it takes 10, 15 years or more we'll keep moving forward