The goat in the picture looks larger than 12 lbs. Can you get a current weight? You can stand on a bathroom scale first with the baby, then stand on it with out the baby and subtract the smaller number from the larger one.
I would have guessed our young boers to be much less than they really are since they are really compact. I had estimated 13-15 lbs for one that was actually over 20! While not perfect, I use the bathroom scale to weigh anything under 100 lbs (I have big boys that can easily lift that much), so at least I can see progress in our kids.
Based on nothing more then the photo, that goat "looks" fine. However if it's only a fpot tall there's a mutation or something else present. * Following for further information.