Hi Dread Pirate;
I underwent TKA in Dec 2010 at age 46. I had end stage Degenerative Joint Disease, and had absolutely no cartilage left in my knee--it was bone on bone. In my case, I was in less pain 1 day post-op than I was prior to surgery. If I remember correctly, I was able to lift my leg without assistance within 3 weeks or so.
Each person is different, obviously, but since you aren't able to lift your leg by now, I would definitely
tell your doctor. Also, maybe try to do your own physical therapy at home as much as you can tolerate--along with continuing to use the CPM machine. I increased my range every 3rd day or so, and gradually was able to get up to 90 degrees. Perhaps doing both will make a positive impact on your range of motion, and recovery. Since you are able to bear weight on your knee while walking, maybe it would help to keep walking--again as much as you can tolerate without pain.
9 days ago, I had to undergo a revision of my TKA. There was some instability that developed in the joint components, and my ortho doctor had to replace them. So, I'm back in recovery too.
I am by no means a health care professional, and your doctor's advice is vital. However, I have had many surgeries in my lifetime, and I can only share my experiences.
I hope you will start to get better soon!