I can't tell you what to do either, but I have always been told that surgery is more successful when it's done to treat leg pain and less so to treat low back pain. I do think I know how you feel, though. I do get a lot of nerve pains, but even when they're not too bad, I get terrible pain in what feels like certain parts of my spine. It's very deep, localized pain, and feels almost like a very severe painful bruise is inside. I also get parts of my spine that just feel "inflamed". I'm not sure how else to describe it. I also have severe OA in my right ankle and have had many bouts of severe inflammation in there. The feelings I get inside my spine sometimes kind of feel like that. Very pressurized, like I wish I could pop it and release the pain & pressure. Sometimes in my sacral and SI areas, I get the same thing. It feels like I've been kicked by a horse or a fastball a few times in the same area and all of it comes and goes. Well, it's always there, just there are days that's it worse and less worse.
Also, before my spine surgery, I had multi-level spinal stenosis, partly due to some disc herniations, among other things. All of this caused me neurogenic claudication. Not saying you have this, but if I tried to straighten in the least bit, the pain inside the low back and even down my legs was unbearable. It felt like there was a permanent vice grip around my around everything inside, with terrible squeezing pains. So when you mentioned your S1 area feels like it's being squeezed, it reminded me of the claudication I had from stenosis.
Does that squeezing pain get even worse if you try to bend backwarRAB? Does it feel any better if you lean forwarRAB?