It is common for most mummies to have backpain during pregnancy as our body are adapting to changes and baby is growing. You are highly advise to use maternity support, maintain good posture,use cushion/pillow when resting or seating and do light stretches.
Maybe you can try seeing a chiro. I’m seeing Dr Dennis Lin at Live Well Chiro @ TPY and I found it helpful. Alternatively, consider a maternity pillow to help with better sleep.