You have to have a TLIF at L5-S1? What reason did the surgeon give to that demands a fusion surgery? Do you have neurological compression that is causing irreversible nerve damage? Do you have an unstable slip that continues to progress?
I think you need to read the section under “Conditions”- “When to have lower back surgery”.
Surgery is designed to reduced pain in an unstable segment. Your pain level and intermittent nature of pain along with good relief from ibuprofen makes me think you need to start asking questions of your surgeon as to why you need surgery.
Now- if you have underestimated your pain on this forum and the pain really is debilitating, that might be another story but by your description, you need to really think about the surgical path you are considering taking.
By the way- instrumentation is generally left in as it typically does not affect the patient. I take out instrumentation in about one in every thirty patients with fusion.