Children.....Why do they have to grow up so fast???

Lately, NOW more than ever, I have been sheding quite a few tears. My kids are growing up way to fast. I'm really struggling with this, and I'm sure there are a lot of you moms out there that are going through the same thing.
My oldest just got baptized and will be going into 3rd grade this year. My little girl just turned six and will be heading into the 1st grade. My youngest will be turning 4 in 11 days. I am done with the diapers, done with the potty training, done with all of the baby stuff, and honestly, I miss every single bit of it. I'm so happy that there growing up and healthy, I just can't believe how fast it all went by. I'm sitting here all ready for church and now I am going to have to re apply my make up because of the tears running down my face. Does this mean I want more children? I don't know, I wish I had that answer right now. I would love more, I just wish I knew whether I am done or not? How do you know? If anyone out there has the answer, I would love to here it.
Every night my youngest snuggles into me and says, as he's holding my cheeks between his sweet little hands, " I like you Mommy, your my best friend!" It just melts my heart. He's always looking up at me with those big blue eyes after he has done something wrong and I've gotten after him and saying "Mommy, I like you in a sad voice, Do you like me? Wow, if that doesn't tug at your heart strings! He's already wiping off my kisses. Why? But, I guess with all of the sad things, there are luckily so many more happy things. Britton is such a character. He's always pulling a goofy face or dancing around all goofy. He's a sweetie.
Maci Bo is very gentle and loving, she is our cuddler. She is starting to get more independent and wanting to always have a friend over or be at a friends house. She is all girl and then some. She loves making hair bows with me and putting on makeup, etc. When she was a little bit younger she was sitting on the sink in the bathroom while I was doing her hair, and I told her how beautiful her big blue eyes were, and that they matched her shirt. She told me that she hated her blue shirt, she said " Mommy do you think that if I wear pink everyday my eyes will turn pink?" She didn't want blue clothes, or blue eyes, because she thought it made her look like a boy! Cute huh? She's our little doll!
Tan the Man is my oldest. He is such a good boy. He still does and always has let me give kisses and hugs whenever I want to. He loves hugs from me every night before bed time. He has always done and said some of the cutest things I just wish I could remember all of them. When he was just two years old and maci was born, the first time he seen her open her eyes, he let out this cute little shout, and said " Mommy She's gots eyes. Isn't that adorable. He also was quite the little waver. He couldn't have been no more than 1 yr old, and we were driving to salina to visit my parents, and we drove past a diesel and honked the horn, and Tanner woke up from a dead sleep and looked out the window and waved at the diesel. He loved to wave and honk the horn, that was his thing.
Over the last 8 years, I have thoroughly enjoyed raising my children and look forward to all of the fun times ahead. I just miss their cute little bums waddling around in their cute little diapers, and the sweet innocent looks on their cute cute faces. The Ma, Ma, and Da, Da, and Mommy Are you. Wuv you, the tiny hands waving for the first time, their first steps, their first tooth, crawiling, first hair cut, first time going to school, those firsts are gone for the most part. Here I go crying again. I love my little monkeys. They are my world and I am so blessed to have them, I'm just having a hard time letting them grow up..........