I am 4 1/2 months from having a total knee replacement, and still have the symptoms you are explaining. I really thought that I would be further along at that this point, but I suppose I was a little naive. I go to PT, do muscle strengthening exercises attend aquafit classes, ride my walking bike outside and my stationary bike inside but walking long distances can give me grief. And that I resent because the main reason for having the surgery was so I could walk without limping after half an hour.
I still have inflammation around the knee and a Bakers Cyst behind the knee so I know the swelling is making it difficult to weight bear. I started to wear an elasticized knee brace which helps and yesterday I got fitted for a compression stocking
But what I wanted to mention is that when I had extreme pain in the first 2 months the opioid I was prescribed did not bring me any relief. The only thing that helped was Lyrica, which focusses more on nerve pain. I can tell you it was a game changer for me and I don’t know why more orthopaedic surgeons do not prescribe it regularly. At the height of my pain I took 150 mg twice a day and then weaned myself down to 50 mg twice a day. Occasionally I might take one but I highly suggest that the people who are having extreme pain to ask their doctor for this medication rather than an opioid. The doctor might be more willing to prescribe this as well as opposed to an opioid.
Another consideration is to take Calcium and Vit D supplements for bone strengthening. Here is an article that supports the use of the supplements
https://www.lancasterortho.com/news/calcium-vitamin-d-your-new-knee.html