www.car-seat.org is a great site. It's run by certified carseat installers. There are quite a few local Portland/Salem techs.
Just yesterday I turned my 20 month old forward facing. She is about 26lbs. I would have left her rear facing until closer to 30lbs, but she has been so cranky in her seat that I thought I'd turn her and she is much happier. I feel better that I left her RF as long as I could -- 9 months longer than most who turn at a year and 20lbs.
IMO -- I'd leave your DD rear facing as long your seat permits.
We have the Britax Marathon which is a great seat. Goes RF until 33lbs and FF until 65 with 5pt harness. Although kids usually outgrow seats by height before weight.
We moved our 4yr old out of a Marathon in July and she's about 42lbs and 41" tall. We got our 4 year old a Sunshine Kids Radian 65 -- I would recomend it highly. It also can be used RF (not sure of stats at this moment). Per others recomendations avoid the Radian 80 which uses a 5pt harness until 80lbs, because it's the same harness height as the Radian 65 (and chances are your child will out grow by height first).
My #1 desire in a car seat is that it have a 5pt harness. You'll notice alot of convertable seats only use the 5pt harness up to 40-45lbs then you use the seat as a booster with just a seat belt.
I hope this helps.
E.