How do you measure a year?

Sadie woke up screaming tonight, and when I picked her up and sat in the chair to try and calm her down, she collapsed in my arms asleep. All of the memories of the past year came flooding into my head and I started to cry. She was lying in my arms asleep like the first time I held her, and I didn't want to breath for fear that the moment would end. Her first birthday is in two days. TWO DAYS. Where have all those moments gone? I remembered the first weeks when we would sleep in front of the fire on the couch. I remembered the spring nights when I would rock her to sleep with the windows open and warm breeze blowing over us. I remembered the first time Ben met his sister, her first smile, her first laugh. In the last few moments of her officially being a baby, I actually got to hold her like I did when we first met and I didn't want it to end. When she finally squirmed in my arms, wanting to be back in her own crib, I remembered all those nights when my arms were so tired from holding her, that I wished she would let me lay her down. Now I wished, just this once, she would need me to hold her longer. I thought about laying her down for a nap today, and seeing her smile and wave to me as she put her head down and I closed the door. Why do we spend so much time wishing they didn't need us? Didn't need us to rock them, or cuddle them to sleep, or hold them until our arms ache. They grow so fast. I wish I could know their lasts. We record the first time our children learn something new. But these aren't the important moments. The ones we should be able to hold onto are the lasts. Maybe if we knew, we would appreciate them just enough to never regret not holding onto them when we had the chance. When was the last time I could pick up Ben, or the last time he could fit in my lap? When was the last time he needed me to help him get dressed, or help him into the car? What about the last time Sadie slept on my chest or sat leaning on me as I rocked her to sleep? When will be the last time they believe in Santa, or run back to hug me goodbye? What if I'm too busy to notice? What if I miss the lasts?