She hasn't QUITE outgrown the Marthon. The tops of her shoulders are about an eighth of an inch below the straps, and her ears don't quite reach the top of the seat.
I think a high back booster is probably the best option for her, too.
My younger child is ultra, ULTRA safety conscious and is terrified of any possible danger. She sits VERY well in the booster with Grandma. However, I think a five point is probably the best for her.
However..... She's a kid with a LOT of anxiety. One of her big fears is being forgotten. She doesn't have a lot of hand strength, and she can't unbuckle herself from her Graco seat, nor any of the other five point seats I've tried her in. (My husband once forgot to unbuckle her at a park and walked off. He thought she was behind him, but realized after about 60 seconds and came back, but that was enough. It was at least 18 months ago, but she still gets a note of anxiety when we park. "Mommy, don't forget to get me out. Mommy, don't forget." For goodness sake, *I* didn't forget her! But, it's pretty sad and pathetic.) So, a big part of me would like to have her in a high back booster so she can be more independent and have more control.
But.....safety wise it's a close call. I'm not sure what to do. Thoughts?