I made this dress last year for my granddaughter, but it was too big for her. I forgot about until now. I wove in the loose ends and added the buttons and it fits her perfectly now. I crochet on the loose side, so I should have checKed the size before I finished. The yarn I used was Deramores Stylecraft Special DK Lucy from Attic24 color pack here: http://www.deramores.com/stylecraft-special-dk-colour-pack
I used most of the colors. You can tell in photo which ones I used. If I remember correctly, I think I made the 12-24 month size and used the recommended E hook. The stretch of the yarn and my tendency to crochet on the loose side made the dress closer to a size 4T.
This pattern was easy to follow, even last year when I had little experience reading patterns. Now with more experience I would have used the recommended cotton yarn as the stretch in the acrylic makes the straps too long from the weight of the dress. To solve this problem, I added decorative buttons on the outside of the dress and buttons on the inside of the dress to attach the straps to, so they could be adjustable.