Pain killers not working for severe degenerative knee osteoarthritis

Hi, I'm new to the group and would really welcome some help / advice. I have been diagnosed with severe degenerative osteoarthritis of the knee and am waiting for a date for a TKR. Over the past year, I have seen a private physio (NHS was taking forever to send date!), and am still seeing her about every 4 weeks; I have had a steroid injection and effusion drained (38mls) privately (the injection didn't work but having the effusion drained did for about 5 weeks and then it started to reaccumulate unfortunately. I have been taking Ibuprofen and Paracetamol for the last few months and have purposely resisted going on codeine as I don't get on well with it. As my pain has intensified and mobility decreased over recent weeks my GP has started me on Naproxen 500mg a day which has had little impact on my pain levels so far but I have only been on it for 2 days. Unfortunately I can't take a higher dose as I am 75 and Naproxen is not generally recommended for elderly patients. I'm so disappointed the Naproxen doesn't appear to be helping and am getting increasingly anxious that I will always be in pain even after surgery. This past year has been one disappointment after another always appearing to be in a state of being going one step forward and 100 steps back all the time. It's had / having a significant impact in my emotional and mental health and I'm on the verge of tears and in a state of anxiety most of the time. I apologise this is a very long post but I really need help and advice from people who understand and are going through the same. Thank you for taking the time to read this.