Hi DeeDee
I'm only a few years older than you and had both knees done, but can totally relate to the heavy feeling and slow progress. When I am having a really down day, I often make myself a list of "what's better", even if it is small. You listed a ton of good things about sleeping, walking without assistance, etc. I've had to go as small as "I can lift my leg on the bed unassisted", etc. I'm still using my walker at 7 weeks. I never expected that I would - thought a few weeks and I should be good to go. I like how your PT was able to explain how long things took to get bad, so getting better is not an over night process. Hang in there and watch each day for the little ups that eventually add up to progress.
Take care,
Stacie