The baby food won't have the same nutrients, but you can blend kitten food in your blender and mix it with water to make your own correctly formulated mush. You can also get nutrient paste from most pet stores to add in to give her more calories. The water added won't hurt especially if she's getting dehydrated. You can even get kitten replacement milk to use in the blender instead of water.

Usually eye discharge means a upper respitory infection(extremely common in cats, esp very young kittens). Make sure she stays warm and out of drafty areas(not that most places are very chilly right now, with the hot weather).