It is possible that out of your concern you are making the Issue worse, it sounds like a lot of reaction from you, I think if you let her eat and be in control of her self it may work better , put the foods out dont talk about your concern about how much she eats , leave her to get on with it, you may find she will eat more, you may unwittingly be creating a problem ,all the talk about how big the portions are , its too much..Back off a bit ,it may work ...