I also find the bedroom in the south suboptimal. Swapping it with the bathroom makes sense. I would move the bedroom/dressing room to where the office/bathroom is now, the bathroom to the south; the study to where the small children's room is now and also give this child a bit more light. Additionally, the children's rooms should be the same size, possibly I would consider a small children's bathroom and definitely plan a bathtub in the bathroom.
Am I seeing it correctly that you have an eternally long driveway to the garage? Would it perhaps make sense to place the garage at the front? I'm thinking especially about snow removal in winter before you get out of the property. The driveway to the house is okay, but I would plan the garage somewhat closer to the street (says someone who still can expect lots of snow).