How long did you use your infant seat? I am trying to figue out if I should buy Graco Snugride that holds up to 22lbs or the Graco Snugride that holds up to 30lbs? Someone just told me you use the infant seat for 3months then buy a new carseat. I thought we would use ours 6mo-1year then buy a new carseat. I know we would not be carring a 30lb baby in an infant carrier but did you use it solely as a carseat before you bought a new one? I hope this makes sense.