Hello
@Gardengirl21 - and
Complete recovery from a knee replacement takes a full year, no matter how much you wish it could be faster. There's good and bad in that. The good is that you still have more than 6 months for your nee to improve. The bad is that you may have to decrease your activity for a while longer.
I think the root of your problem is that you are trying to do too much, too soon, and your knee is swelling because of that.
In spite of what you've probably been told, there's no need to rush to get ROM (Range of Motion) because it can continue to improve for a year, or even much longer, after a knee replacement. There isn't any deadline you have to meet:
Myth busting: the "window of opportunity" in TKR
In any case, as sistersinhim said, it's not exercising that gets you your ROM - it's time. Time to recover, time for swelling and pain to settle, and time to heal. Your knee has the potential to achieve good ROM right from the start, but it's prevented from doing so by swelling and pain. As it heals and the swelling goes down, your ROM (both flexion and extension) will gradually increase.
My suggestion is that you stop going to PT, stop doing formal exercises, and just let your normal activities of daily living be your exercise.
it's really too soon to be expecting to do gardening, so reduce the time you spend doing that.
Instead, spend more time icing and elevating your knee, to try and reduce its swelling.
All the pain and swelling you've been experiencing are a message from your knee, that you're asking it to do more than it is ready for. Listen to your knee. It knows what it's doing.