Good for you Sweetpea. It's not easy to lose weight especially as we get a little older. It took me just over 9 months to lose 20 kgs. I got down to 65.5kgs then put 2kgs back on over Christmas. I'm trying to move those last 2kgs but would ideally like to be 64kgs.
It's no secret that I went to Jenny Craig and although I stopped eating their food some months back, I still follow their basic programme for the most part. I've lost it sowly and the theory is, if it comes off slowly there's a better change of keeping it off.
Not sure what you're like with exercise SP with your knees. I have been unable to exercise so it can be done without!