Where did the time go?

So I have to tell you that my 8 year old still (on a rare occasion) sleeps with Mommy and Daddy. And I have to admit, I still like it. Last night she asked if she could sleep with us, since big sissy was at a sleep over. As we lay in bed, Kate snuggled up next to me, I started to wonder where did the time go? There are so many little things my kids did that I can't remember. Is this normal? I as a mother feel that I should remember everything that my kids ever did when they were younger. Sure I can remember their first steps, and crawling and other major things.
Poor Kate, when she came along my older daughter was 2 and she still required a lot of attention, therefore I think I forgot little things that Kate did? This makes me so sad I wish I had a remote and I could turn back time and watch everything over again. I guess that is what home movies are for, and it is good that we have a lot of them. Every so often my oldest will ask "Are you sad that we are growing up?" I want to tell her the truth "It hurts my heart so much to see you grow more and more every year" but I don't want her to think for a minute that I don't enjoy them growing up. Don't get me wrong, I do enjoy them growing and watching them have their first dance, boyfriend, sleepovers, long phone conversations (lots of texting) and everything else that comes with the territory. But I do miss holding them on my lap, watching their sweet face as I feed them a bottle, discovering things for the first time and talking baby talk. So as much as I don't like time flying by me I will cherish all the pictures, scrapbooks, and video when they were babies. I will also cherish all the times I have now with them growing up and still discovering things for the first time. It's the little things in life I wish I could remember.