Car seat (graco all in one smart seat!)

Bethany
Ok I have a graco all in one smart seat....
My daughter is 3 years Plus 1 month she is 27 pounds and 3ft 1 inch
The seat doesn't specify height for read facing it just says head needs to be one inch under top? 
Does anyone else have this car seat when did your child outgrow the height would like to keep rear facing for protection as long as possible but if it's not safe because she outgrew I wanna flip her???
Please anyone know?