I think your plan sounds good. The Nautilus is a good seat. It's way too early to know whether it will fit your DD well as a booster. You'll have to see how it fits your DD down the road - probably when she is about 6 years old and closer to the limits of the seat. However, you could use it as a harness seat for about 3 years and then pass it along to the baby to use as a harness seat if you decide it doesn't work as a booster.
I just bought a booster seat that was on the neutral list - the Sunshine Kid Monterey - and it fits my top of the charts tall DS great.
thanks for your response.
so you don't think I should be worried that the nautilus isn't on the good list? why do you think it isn't? I can't help but worry, but I see so many recommendations for it.
My booster seat is on the same list as the Nautilus. It's not on the good list because it doesn't fit as many kids in as many vehicles. It's going to fit some kids in some vehicles perfectly and other kids in other vehicles not as well.
I still think it's a great option for you. If you decide the fit as a booster with your child and your car doesn't work, you have a great harness seat to pass along to the baby.