Are you on a bone anabolic. Many surgeons prescribe Forteo or Tymlos in anticipation of surgery. Both medications increase T scores, speed of healing after surgery and enhance integration of surgical hardware.
They also increase chondrocytes in disc cartilage. I haven't tried PRP, but opine that it couldn't hurt. I wonder though if your pain would be lessened by facet joint injections, until you qualify for the surgery.
I would also have a second opinion. You might look at artificial discs instead of fusion.
Hard to do anything with a headache. Best wishes.