Hi Leonie, our Aussie friend!
I'm sorry you're feeling down and that you are frustrated.

You're right in the middle of the time when that happens to most of us, so go ahead - yell, cry, moan all you want. We'll understand, because we've been there!
It's so very hard to believe that you will recover, when friends and family expect you to have bounced back by the time you reach 6 weeks. That's because most of them simply don't understand what a very major operation a knee replacement is. They've only seen people recover from other operations, many of which do only take about 6 weeks to recover from - but this is different. Add to that the fact that most of us probably had the same expectations as our friends, so we probably beat ourselves up about our slow progress.
This recovery is more like a marathon than a sprint. We're in it for the long haul, so we can't rush it. Our recovery is strange, too, in that we do seem to take one step forward and one step back so many times. But we do make progress in the end.
It's very hard to be patient, but patience really is your best friend. I wish that there was a Patience Fairy, who could wave her magic wand and give us all the patience we need. She'd be a very busy fairy!
Now, about your pain - I may be wrong, but I think your knee is giving you a message here, to ease back on your activity. Maybe 2 days of physio and one day of pool are just one day too much at the moment? If you find the pool therapy really helpful, perhaps you could cut back the physio to one day a week? You can still do gentle bending and stretching exercises at home. Keep up the resting, icing and elevating.
Also, you are still taking pain medication regularly, aren't you?
Lack of sleep - ah yes! That's a frequent problem too, another of the "joys" of recovery from a TKR. Try not to worry about it. Take sleep whenever and wherever it comes - be it in short bursts at night, or in naps during the daytime. I used to look upon the long nights as just time for reading, watching overnight TV, just pampering myself. I moved to another bedroom so I didn't disturb my husband. As you progress, good night-time sleep will return.
Hugs!
Caryl