Tanya, I wish there was some way that a person could know exactly what is the right thing to do, but that's not how life works. You look at your options and make the decisions that are right for yourself based on what you know at the time.
However, with arthritis....as Celle says it doesn't ever get better - only worse with time. So if you are having problems now with your knee, you do know it will not improve unless you take some action. Of course losing weight might help things, but it doesn't sound like that's been easy for you to do. That happens to many of us when joints start going bad, so you're not alone.
I'm glad you're getting a second opinion from another surgeon as it doesn't sound like the first one you met with was a good match for you. Be sure and share all your reservations with him during your consultation. I hope this doctor is more tuned to his patients' needs. Most people need a little reassurance.