Tt40 - my DS is 10mnths aand 75cm and nearly 10kgs so a big boy and I have him rear facing still. I took a small insert piece put from between his legs first and then took out the newborn insert after that probably a few months ago now so maybe 8mnths but it gives them ALOT more room to grow in height markers. Take it out and see how she fits in it. My DS didn't notice a difference I don't think and still sits rear facing no problems.