I also think he's a wee bit thin, BUT I do agree that it's much better for this breed to be lean, especially as they grow.
As N Smith said, the first pic isn't great because they suck in as they eat or drink.
It's really hard the first year when they are going through growth spurts. Are you feeding him in one sitting? It might be too much food at one time, maybe split the feedings up. When my pup was your pup's age, I split her meals into three feedings.