Beth, please listen to Jo. Her words are exactly what I was going to say. You have fallen into the trap of trying to compare your current recovery with others' and with your other knee. But it's a UNIQUE surgery and you must look at it that way and deal with what is.
And what is......is that you are in too much pain right now. And the pain is resulting is swelling in your knee and leg. Once you get the pain under control, you can deal more effectively with the swelling (ice/elevation/rest). There are no other solutions. You need to take adequate amounts of a prescription pain medication on a regular basis.
My suggestion is to go back up to your regular dose of the oxy until you have at least two entire days where you feel your pain was managed. Take the pills on a set schedule (whatever the maximum dose is on the label). Along with this, you'll need to get plenty of rest with ice and elevation. If you start feeling a bit better, this is NOT the time to increase activity. Your goal is to simply get on an even keel again.
Once you have a couple of good days under your belt, you can better judge what level of the medication you need. BUT....whatever that dose is that keeps the pain at bay, take it on a set schedule whether you hurt or not. Don't try to cut yourself short.
As Jo says, if your surgeon wants you off the oxy, ask for a step down drug like Percocet, Hydrocodone or Tramadol. There are many options. And if he won't agree, then Jo's advice is right on target. Get to your GP and get help there. Your number one priority is to get your pain managed. All else will follow once you have that going for you.