So my almost 7yr old rides in a Turbo-booster (with the back). She is 48 inches tall and 53lbs (just measured/weighed today). I'd like to keep her where she is, but when she's riding in the seat and we turn, her seat tips to the side. I've tried putting it in one of the captains seat in my van instead of on the bench seat, and it didn't help. Is there anything I can do? It makes me nervous to see it tilt like that.