Lynne, you are barely 2 weeks out from surgery. Ofcourse your knee is stiff and probably continues to have swelling which makes it stiff. There is a lot of healing going on----most of it is going on inside---so even if your incision looks great--there's soft tissue, bone, muscles, ligaments, and nerves that have been assaulted and will take TIME to heal.
And you cannot rush the rate at which your body decides to do that healing. PT is necessary to help facilitate your range of motion, build muscles back up, and for some to reeducate gait. But too much PT or overly agressive PT will make all that soft tissue angrier than it already is and more swelling and less healing will take place.
Yes, you should take the days inbetween your PT sessions off. Just whatever walking needs to be done and very gentle bending and stretching. Also do not allow PT to hurt you---a little discomfort is okay, but pain is a big NO-NO.
Some of us have trouble with extension and others with flexion and some (the lucky dogs) have no trouble with either. For the most part if you continue on a regular basis to do GENTLE stretching and bending, the full gamut of ROM will return.
Your body is using all your energy to heal. So there's very little left over for the things you want if for. It will take TIME for it to return.
As you can see, TIME and PATIENCE, along with a little reasonable PT are what it takes to get through this recovery. Most of us don't have a lot of patience and don't think we have the time, but we really don't have much choice.
I am fortunate--I got old and I could retire--so I got more time than most anything else and have acquired patience. But if I had had to go back to the job I had, I would not have considered it before 16 weeks. I am now starting my 24th week since surgery and still have stiffness after sitting for long periods, knees still tender to the touch over the incision, have some swelling if I overdo, and still cannot go down steps foot over foot. I still have to ice and elevate occasionally. I am sleeping pretty well and have a good energy level. I almost feel "normal" again--not that I was normal before the surgery---but you know what I mean.
Take care of yourself & keep us posted. We care. Judy