Thanks for all of the advice girls. It seems to have worked for now. At my antenatal appt today, the ob said he has turned (I though he had I had some BIG movements in the last day or two!) and is laying on my left side, which is great for labour. I am more comfy and my back is no longer sore all the time. I didn't even get up to pee last night which has to be the first time in weeks, maybe even months! LOL.
I will continue with the bum up position a few times a day, and I'm conscious of my posture.