Sleep sack finished

I finished the sleep sack tonight but I think I might tweak it a bit more. The pattern called to cast on 128 stitches and after a few rounds I realized that there is no way that this was going to be small enough for a newborn-6 month size so after finishing the waistband I increased by 20 stitches and added about 2 inches of length to make it a good size for 6-12 months (that is when we really ran into sleep problems with Baby C waking up cold because she rolled out from under her blanket). I think that the waistband is still a wee bit big for that size and I'm not quite sure what to do about it (any suggestions). I might just add a crochet collar for about 1/2-1 inch to tighten it up... but it might also look like crap. I guess I'll have to try it out and see how it looks. I have enough wool left over to make another so I think I'm going to go back to the drawing board and make a smaller newborn size.