It's amazing how much children learn when we aren't pressuring them to learn and I think they learn the most when they are having fun or when they are really intent on finding an answer they want to know.
Most babies survive even when they seem to have no appetite. The best advice is to be sure that the snacks your child gets are nourishing because it would probably surprise you how much she is eating in snacks.
I was amazed when I watched my grandchild doing math when she was very young. I can almost see how it is done because I feel it is intuitive to know the number of items at times.