My baby isn't a baby

Perhaps it's because of his tiny beginnings, or that he's our last. But I'm having hard time believing how fast he is growing. I sometimes forget to stop and look at my children and how big they are. My daughter had the longest legs on a five year old I have ever seen. She is such a little woman. I had my first real mini conversation with Logan this week. I asked him what he did at Mimi's and he said, 'A bath". It's the first time he has answered without a yes/no and we have understood him. Then on top of that he started Sunday school this week..  KayLynn seemed older when she started. In less than two weeks my baby will be two, and soon after KayLynn will be six. I'm having a hard time grasping this.