Hi Kirsty
I’m 18 days post op and my lower back is hurting too. I find my posture has altered slightly which I hear is normal as your body gets used to the new weight, and also it’s almost like you slightly hunch over to protect your chest, but also sleeping upright is bad for my back. I have a pillow to support the lower part which helps, but find the only effective pain relief for me is co-codamol.
Hope you are doing ok x