Carseat shopping...And Growing Pains (yes they go together)

So last week our youngest (Cooper) went for a check up. He was going for the six month once over. Actually considering he was 5 weeks early they check him more as a 4.5 or 5 month old and will continue to adjust like that until he is about 2. He checked out just fine not rolling over yet but hitting his mark everywhere else. He weighed in at 16 pounds 27 inches long. So my pediatrician said it was time to start shopping for a new car seat since our seat weight limit was 22 pounds. He recommended the Britax Marathon. And I almost just went ahead and bought it but decided to research and ask around first. And boy am I glad I did. I just didn't know how many convertible seats where out there and the price range is wide. I spent hours (yes, hours) looking at seat after seat on line and asked almost all of my friends with young ones what seats they had used and the pros and cons. I kept hearing the same thing about the Britax-it is a great seat with a high weight limit but most kids out grow it before they reach the weight limit. So i searched on and on. I was so surprised how many different kinds there was to choose from out there now. I found one I really like that could be re-facing, forward facing up to 40 lbs and then be a booster and I read alot of reviews and thought it was going to be the one for us until I read other reviews at another website. I realized it was not the one for us and the search continued. A couple of hours later I found "THE ONE". It is the True Fit by The First Years, I read all the reviews I could find on it and only found a couple "bad" ones about how it was hard to install re-facing in small cars (not a problem for us we have a van). So the decision was made we are getting it for Cooper and we can't wait. Only problem is new seat means he is growing up and I am not so sure I am ready for my little baby to grow up it is happening way to fast. I was not prepared for how fast this time was going to go by. I didn't remember the time passing so fast with the other two and this makes me a little sad! I know it is going to happen but where does the time go and the "growing pains" are worse for mommy then for baby. And the more I think about Cooper not being a baby anymore the more I think about how Jesse-Grace will be driving soon and Duece will be having girlfriends and how before we know it this will all be a blur of memories. I think that for now I am going to seize the day and enjoy this time because one day it will all be over. Ugh what's after all of that grandkids don't think I can even imagine my sweet little ones with little ones of their own.