It's not really that empty. There is an abundance of details. But they seem to be put in there without logic. Also, If you don't need some space, just put trees or water in there. Enlarge the badge of long grass in the bottom right corner. Adding something vertical would help too.
Or just go with it as it is. There are prolly other things, which you need to do in order to finish the game and you can always return to maps.