Something to help...
As pregancy porgesses, it will sag lower and strain your back causing pain etc.
..Some stretching, proper positioning is important; rest on your side when u can. Also, u may consider a maternity belt for some support, just don't pull it too tight.. A soft backbrace in conjunction with maternity belt may help.. Add warm back massages.
Consult your doc for additional help..
Good luck and congrats..