Wasn't sure if that one was yours!
The lifejacket seems to be a big issue - Mia hates it, and from seeing the fit it's not hard to understand. And that was the best fitting one we tried. After growing some she should be a little more comfy this year.
There was a recent evaulation of children's vests that mentioned the uncomfortable fit as a big issue. Also, for some reason infant vests in the US don't have harnesses for a tether built in, while in Europe they do.