Oh man, I have a very similar story to you. I broke my tibia in 2017 skiing. They did the whole take my knee apart and put a rod inside my tibia and screw it together down by my ankle and up by my knee. First surgeon didn’t get things lined up very well, my foot was pointing out to about 2 o’clock which was causing all kinds of issues. Also didn’t fuse on the front side because of how big of a gap he left. Had a second surgery in 2019, they removed my lower two screws and had to re-break the back side of the bone that did fuse, straighten everything up, sand paper the part of the leg that didn’t fuse because apparently it had smoothed over, got a bone graft from my hip and donor to help it along, and then they bolted me back together, this time the screws are in the front not on the inside. Nearly 10 years after the initial break and I deal with near constant pain. I found your post searching for “I want to amputate my leg after tibia fracture”. Ugh, I am so sorry you are dealing with this. I wouldn’t wish this on my worst enemy.