I would like to comment on your MRI findings:
“Mri's show degenerative disc at l-5 s-1, grade 1 spondylolisthesis, and severe spinal stenosis”
If a spondylolisthesis (a fracture of the pars of the vertebra and subsequent anterior displacement of the vertebra –sorry for the technical jargon) is resulting in the stenosis that is causing your sciatica, then you need to stabilize that segment. Stabilization may come from specific exercises (research by O’Sullivan showed a benefit for spondylisthesis patients suffering from back pain), supports, or in severe cases surgery. Your listheis is not severe, but your stenosis and symptoms are. There is a good chance that you may require surgery.
What level of pain are you in (using a 0-10 scale)?
Surgery would be considered successful if you were to lower the pain to 3/10.
Epidural injections have helped sciatic sufferers. But are far from a magic bullet. Studies show that 1/3 of patients with sciatic neuralagia can expect a 40% reduction in symptoms with an epidural injection.
You may want to try using a strong lumbar support, not for treatment , for diagnostic purposes. If the support is helpful then you have a pretty good idea that you need more support. Be careful about long term use of belts.
Are your symptoms worse with prolonged sitting? Standing?