M.F.
K.,
That is a problem, I wouldn't want thing in between legs if it were too tight. The only thing I can think of: Are her should straps up at the highest level already as well? If not, try moving those up (they should be even or a tad higher than her shoulder). If you move those up this would allow her straighten up more and sit fruther back in the seat...just my suggestion, otherwise I am not sure what to do...other than the booster, they have lots of those that have the 5 point harness but not sure about what size the child should be. We only have an 18 month old, so these problems are yet to come :)