Convertible Carseat Confusion!?

My daughter is just very long so we had a similar problem. I know another person said it already but we have a Safety 1st Alpha-Omega Elite 3-in-1 that we love. It is pretty long, but supported my daughter well both rear facing from about 4 months through front facing now at 12 months. They say it will last through about age 8, which I doubt, but it will last quite a while.