Oh, I hear ya. After my left total hip replacement in 2012,....I had spinal fusions and decompressions L1-L5. Then less than six months later, I had a total hip replacement on the right.
Just like you, my doctors tell me I "shouldn't" be in this much pain, that it should all be healed and gone away by now. I get the feeling they think I'm trying to milk this, but the truth is, this is not over.
I did have severe complications (a few of them) after my right hip replacement, and my right thigh is 3" larger than my left, so when I walk, my gait is severely compromised.
That of course, affects my low back.
My neuro (who I happen to love) told me that regarding the nerve damage causing my foot drop, to give it 14-16 months (and in that time, the maximum healing would occur). Because I had such progressive stenosis and structural damage, they did what was called "spinal reconstruction," and he told me to be patient, and to give it up to two YEARS to see what changes will evolve.
For the first ten MONTHS, I was in a lot more pain than I am now. Things are only now slowly subsiding, but activity can kick things back up.
When we have hardware in our back, it's my opinion we can contribute to "failed back surgery" when we don't accept, realize, and respect the fact our vertebrae are fused. Especially with L5/S1, you will never have that flexibility back again,...as with all fusions, but in particular, that region is very tough.
Trying to bend, lift, and twist as if you had a "normal" spine without hardware, will only make things worse.
It may be too soon yet. I would let my body continue its healing process.
If it's nerve pain, you need to be aggressively tackling that in PT because you're on borrowed time, in a window, to maximize the regeneration.
As for the pain,....that can take a while. I'm not sure, but for me personally, I wouldn't subject my healing body to injections or anything invasive until it has the time to fully repair.