A Rush To Grow Up

Savannah has been in A Rush To Grow Up from very early on; She took her first steps at 9 months old and gave up her bottles at 12 months old.  She was less than a 1 1/2 years old when she started stringing words together and she learned how to swim with a life jacket months before she turned 2.  By the time her 2nd Birthday rolled around she had moved out of her crib - and the nursery - and into a twin sized bed in her "big girl" room upstairs.  Most recently, at a smidgen under 2 1/2 months old, she became potty trained.  No more diaper pail.  No more changing table.  No more buying diapers and wipes in bulk on a regular basis.
Suffice to say, she doesn't need any encouragement to hit milestones.  I guess having two older siblings is motivation enough!  Not only does she want to keep up with her brother and sister, but she seems to want to be one step ahead of them, too!
A couple of weeks ago she decided to boycott her booster seat on the kitchen chair.  Despite the fact that it helped her to sit better (and more comfortably) at the table, she would go to extremes to avoid having to sit in it.  When I would call "dinner time!" she'd come running full speed into the kitchen - far ahead of Kyle and Bella - just so she could scramble up into one of the other chairs.  A few days ago I reluctantly packed away the booster.   Sadly, yet another piece of "baby" gone.  But last night, when she tried to get rid of one of the last pieces of baby left, I drew the line.  I put my foot down.  She asked for a drink and when I went to grab a sippy cup she said "No baby cup!  Big girl cup!".  Baby cup?  What the heck?  No one in our home has ever even referred to a sippy cup as a BABY CUP!  She fought me tooth and nail but in the end, she took the sippy cup.  And then it started all over again this morning at breakfast.  Her final "baby" days are hanging by a thread, with me holding on with both hands.   I'm not ready for her to grow up, but she's hell bent on doing just that.
In a couple of days I'll be packing the Van for our trip to Vermont.  For the first time in many years I don't need to pack a diaper bag or a playpen or a booster seat and - if Savannah has any say in the matter - I won't be packing "baby cups".  I don't have to pack a bag of "baby" toys, either.
The only "baby" left to my little Savannah-Banana is her favorite pink "baby bear" and her "blankie" - which is nothing more than random old burp cloths that she snuggles with.
As a parent it is truly bitter-sweet watching my children grow up.  I have a 9 year old who is almost a black belt in Karate.  I have a 4 year old who knows how to ride a horse better than most adults.  My 2 year old thinks she's a 5 year old. 
While I'm glad that they're all thriving, I'm also terrified at the speed in which they're growing up.  Wasn't it just a few years ago that Kyle was toddling around with a binky in his mouth and his "duck" blankie clutched in his hands?  When was did my chubbalicious Bella - with her wild, chia pet hair! - transform into a slender girl with gorgeous, long hair?  And my lord, was Savannah ever even a baby to begin with?!
If not for the scars running all over my stomach as a constant reminder of having carried 3 children I might just question whether or not I gave birth to any babies at all!!
Why are they in such A Rush To Grow Up and how can I delay this process for just a short while?