School Stress!!

Little D has been very stressed about going to school Initially, I thot it had to do with separation anxiety, but now..... I am not so sure. She really doesn't like to go to school. With S, my eldest child, she used to cry (when we 1st started her in preschool) everyday, but only at the time when I left her at school. Otherwise she was fine the rest of the day at home. With N, it was super duper easy. No problems from day 1. Said goodbye happily. With D, it starts the night before. She doesn't want to go to bed. She hates me (coz I am the one that sends her to school everyday). She wakes up in the night crying. Even on weekends, if we head in the direction of school, she will remind us that she doesn't want to go to school. Wont wear her uniform. Cries from the minute she wakes up. Doesn't want to shower. Doesn't want to wear her school shoes. This is really, really stressful for me. Not sure if there will be any psychological impact on her in the future. I worry. How can someone so young, be so aware. None of her classmates have this problem. She is the only one crying in class everyday. I know every child is different. But why is D SO different? Many children would have gotten used to the routine by week 2 or 3. This is week 5!! She knows that I will pick her home at the end of the school day. She can even tell me that. It is not that preschool is no fun. I chose this preschool because the teachers are caring and the kids have lots of fun there. (Sometimes, i think too much fun!) Why, why, why? I just hope things improve soon. I am too stressed out by it. As a result, I tend to be shouting more than necessary at the other 2 children. Poor them. I must watch myself.