I'm not going to explain why you need to use a cane rather than a crutch - because I believe that you are right and your PT is wrong! The time to change is when you feel safe with a cane, and not before. In fact, if you are falling when trying to use a cane, trying to use one is downright dangerous.
the PT has trained for years to do her job and I feel like I really don't have the right to tell her what I should or shouldn't be doing
Graduating from a crutch to a cane at X number of weeks may be in the PT's agenda - that doesn't mean it has to be in your agenda. Your knee is recovering in its own time frame, not on some theoretical one-size-fits-all schedule.
This is your knee, your recovery and your life. You have the absolute right to say what you will, or will not do. She may have trained for numbers of years, but has she had a knee replacement herself? I bet not.
Of course you have the right to tell her what you should be doing! She is putting you at risk of having falls, which would be a bad thing.
One way or another (whether paying privately or through your taxes for a health system) you are paying her. You are employing her. You could even sack her, if that is your wish.
My PT is very gentle and doesn't seem to push too hard. (I cringe when I read some of the awful things that are being done to other Bonesmarties!) But even so, every time I go to see her I end up with a knee that is very, very sore for 2 or 3 days and I can't do anything. My knee is still very stiff and I'm still limping badly if I walk around the house without a crutch. I really want to stop the PT because I'm not all that sure that's it's not making things worse,
On the same theme - if you are stiff and sore for several days after PT, it is not doing you any good.
Do you remember this, from BoneSmart's mantra?
- if it hurts, don't do it and don't allow anyone - especially a physiotherapist - to do it to you
- if your leg swells more or gets stiffer in the 24 hours after doing it, don't do it again
At this stage, you really only need to do a few (very few!) simple exercises and walk around the house as normally as you can. Forget about trying to increase your ROM for a while - it's doing OK and will improve gradually all by itself - and just concentrate on trying to walk properly, without a limp, using your crutch to help you. Reading these articles again may help:
It's never too late to get more ROM!
It's worth the wait for ROM
There's no need to rush this recovery. It's a marathon, not a sprint, and it can take a full year to recover completely, although you'll feel much better long before that.