LO is now 23.5 inches long and almost 14 lbs at just 6 weeks and I'm wondering how long he's going to last in the infant car seat we have, which is the Chicco KeyFit 30. Of course it is supposed to hold babies "up to 30 lbs" but I can't find anything about the length. Does anyone have a LO who is long and if so how long did the seat last? TIA!