@brklimeks Well, dang! I had a reply almost typed out and somehow hit a wrong key, it all disappeared!

There are several factors when we look at the eGFR of kidney function. One, with advancing age, there is a natural slight decline in function level. Two, function level with chronic kidney disease can fluctuate depending on how we are feeling, and the root cause of the CKD. Is it hereditary [such as polycystic kidney disease], lifestyle or medication side effects [high blood pressure or diabetes, or side effects of long-term psychiatric medications, for example]?

You say you took yourself off Spironolactone, which is a high blood pressure medication. Did your dr replace it with something else, or is he aware you did this? As far as Gabapentin, it can cause some issues long term for kidney disease patients, but according to this chart, you are within range: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291335/

Definite medications to be careful of, with kidney disease, is aspirin, ibuprofen, and naproxen. I hope this helps you, and if you have further questions, please let me know!
Ginger