Please research EXTENDED REAR FACING and JOEL'S JOURNEY, and keep your little one rear facing for a couple more years.
Some good seats-
FirstYears TrueFit- $160-$200 rear facing to 35lbs, forward to 65lbs. Very tall seat, great for taller kids. (my almost 4yr old is rear facing in this seat)
Britax Marathon/Roundabout 50-$160-$280 rear face to 35lbs, forward to 50 and 65lbs. Easy to install and use.
Evenflo Triumph Advance- $130 rear face to 35lbs, forward to 50lbs (the newest version is 40 rf and 65 ff).
Sunshine Kids Radian-rear face to 45lbs, forward to 80lbs. (depending on model, some ff to 65lbs)
Graco MyRide 65 $150 will rear face to 40lbs, forward to 65ls.
Look for a seat that will rear face to 35lbs or 40lbs and then forward face to 50 or 65 or 80lbs. AVOID the 3-in-1 seats like the Cosco Alpha Omega, they are short seats, outgrown in the harness fast and make bad booster seats, they are not the last seat you will need and for the money you would spend on one you can get a much better seat that will last longer.
When rear facing the harness should be just at or below the shoulders. The harness should be snug as a hug and the chest clip level with the armpits. A rear facing car seat is outgrown when a child has less than 1" of hard shell above the head or the child goes over the rear facing weight limit.
NO BULKY JACKETS OR BUNTINGS IN THE CAR SEAT! NEVER modify the car seat with anything to make it softer or more comfy. If it didn't come with the seat, don't use it in the seat. That means no Bundle Me's, no head supports, no foam, nothing. If it didn't come with the seat, don't use it.
www.seatcheck.org
www.safekids.org
www.joelsjourney.org
also google EXTENDED REAR FACING.