Could you get a double bed for you and the kids and put it into your DS2's room? Then you and the kids could sleep in there and your Dh could sleep in your bed. Ideally, I would be having a serious talk to your hubby and getting him to help out and sleep with the bigger kids and you can deal with baby. At least some of the time. He's part of the equation too. It's not fair for you to suffer all the time andhe gets to slack off.