Im looking for a carseat for my almost 2 year old. It needs to be one that is easily fitted in the car as im going to use it for when im in other peoples cars (I dont drive) I have been looking at getting a high backed booster. These state that they are 4 years plus, however my daughter is 15.5 kilos which is over the lower regulation to use them (shes very tall) So is this a safe option to use? Opinions and recomendations needed! Thank you