B.R.
My son is 13 months and also thin and long - and the best advice I can offer is just relax and let his develop at his own pace. My son also eats things on his own, but more with my help - and that is perfectly ok for his age. He loves to play with a spoon, but mastering the skills of using it to put food in the mouth is still a ways off. But playing with it is a good way to encourage those skills. He enjoys playing with pieces of food, and sometimes they end up on the floor but I think that is part of the learning process. Remember to make sure mealtime is enjoyable for BOTH of you, and if that means a messy kid then so be it.