I have the VB fitted pattern, and it doesn't actually fit my DS as well as I'd like. But I drafted my own and THAT fits him perfectly.
Here are some easy instructions for drafting your own pattern to fit your child (note: at the time of this writing, Webshots is down for upgrades, so you might need to try later). Although for the waist measurement - I found my diapers needed cross-over tabs when I went by that, since my DS has a milk belly that pushes diapers down below his waist a tad. Also, he had just started walking, so could have slimmed down some, so I didn't want his measurement at that time to be the tightest setting. If you're in a similar situation, you might subtract an inch or two from the width. Try your pattern out on $1/yd fabric first to get the fit and general shape worked out, then try it on real materials.

I had to shorten the tabs and big time widen the butt (mainly because my width was greater than the rise because DS has a big waist).
Drafting a pattern is not that hard really. I was scared to do it at first, and then after reading that tutorial and seeing the pictures, I realized how easy it could be!!!