the harmony defender is a good choice to keep her in a 5 point harness. its low cost is wonderful as well. A high back boost or a boost is not safe for her to ride in due to her age. if she was 5 you could start to train her in a high back booster which is what my son is in who will be 6 in August.

@tiffrae, I just found a new seat because she is very tall for her age but like to unbuckle .. Waiting for her dad to buy it..

you daughter has out grown this seat in height. she's foward facing with the straps below her shoulders. forward facing straps should be at or above shoulders. if you need help finding another seat to keep her in a 5 point harness as long as possible I can help you.