I'm one of those who never did formal PT. Due to birth defects, I've had 12 knee surgeries, 2 of them kneecap removals, and 1 TKR. Even after those, I never took formal PT. But, I didn't just sit around and do nothing, I used my knee as it was intended to be used by walking around to take care of my daily needs along with the necessary house and yard work. As I healed, I was able to do more. Icing and elevation were a huge part of my recovery. If I found that a new activity created more pain and swelling, I would not do it for a week or so, then try it again. One new activity a day was all I would try, that way I'd know what was aggravating my knee. If I didn't have a negative reaction, I knew my knee was healed enough to do it again.
Listen to your knee. It will tell you if you're doing too much by increasing pain and swelling, which you are experiencing. It may benefit your healing if you stop all exercises and use your personal daily activities to be your PT. That is all I did, and I have recovered just fine. I found that resting, icing, and elevating helped. Your knee knows how to rehab itself without being told what to do. Doing too much too soon causes setbacks because your knee has to heal from the inflammation caused by the exercises before it can get back to its normal, after-surgery healing. As Deb said, few PTs know how to rehab a joint replacement. You can do it by using common sense and watching your knee's reactions.