Wow- the surgeon only went to 110*? Is that a functional joint? Mine showed me a picture of my knee totally bent, about 135*! And I did aggressive daily PT after, and with exercises, I start at about 115* before, and reach 125*.
Your story about in home PT and delay was exactly like mine, so I have always wondered if scar tissue was laid down early.
The memory of 2 therapists pushing and bending my knee where I would literally hit the wall backing off in pain. OMG. Couldn’t retain those numbers for anything.

Stairs are still a PIA going down. I’m not happy with my knee but it does walk and hike at least. Very limiting in so many ways though.