I know I'll a little behind the 8 ball by posting this today, but my computer was not being agreeable yesterday. I will be so happy when I have saved enough to buy a new one!!!!
The American Academy of Pediatrics released new recommendations for the use of car seats and boosters that are going to be an adjustment to those of us who have small children. We saw recently the change to older children using boosters longer, and these new standards now are designed to keep the youngest members of our family safe in our vehicles.
I know some (including my husband) think that keeping an older child in a booster while in middle school if they aren't the proper height is humiliating. I think that as this generation in our car seats now will think it's normal and expected, just as wearing a seat belt is now. Just because we weren't required to do something as a child does not mean that it was the safest thing that we could have been doing.
I highly recommend you checking out this article on the new guidelines which also addresses some of the common questions/concerns parents have. It would also be a good idea to look at some of the other resources available on the AAP's site.
I would also suggest that you go to get your seats checked at a safety seat check location and re-read your seat manual. I have seen many seats installed or used incorrectly and it's worth the 15 minutes. The biggest things I suggest you check are: that the latch tether strap is flat and tight, that you apply pressure when installing (I kneel full weight into the seat as I tighten the tethers), the chest strap needs to be aligned over the nipples or the armpits on infants, and remember to attach the top tether to an anchor point (not a cargo loop.)