I'll bet with your son you sat down and rested some yourself while he was napping, etc. Doing daycare we don't let ourselves do that as much as we should. In the grand scheme of things the kids will not be harmed for life if you don't play ring around the rosie for the next 4 months. Keep your schedule flexible and low key. You are actually at the worst part because of the position of the baby. The baby should soon make a drop and then you will sleep, bend, sit, move a lot better. I have 4 kids and I started daycare when my own were 18m and 4 m and the next two were born into the daycare. You need to give yourself permission to look at what is important in your program and what can wait or is just extra fun, you need the parents to be on board believing that continuity playing with friends for a few months is more important than visits to the museum and recreating a lunar escape in the playroom. Again give yourself permission to proceed slowly.