I hacked apart a couple old button down shirts and sewed up this apron for my kiddo's Christmas. The apron front is the back of the shirt, so it was already fitted, and it's backed with some muslin I had sitting around.
It fits perfectly.
The top strap is made of the button hole panel, so it's totally and completely adjustable. The pocket was hacked off a girl's shirt and sewed directly onto my apron of fruity goodness. I'm not great at it yet, but it's wearable. Tada!
in this pic, the adjustable strap is just hanging, but when worn it doubles back and buttons on the button one more time (as in first pic)