I agree with pp...do not engage in any power struggle over food, the child will win every time, because you cannot force them. Keep offering, give her the things you KNOW she will eat, right along side what she used to eat, and some similar things to what she is eating. If she likes toast, give it to her, but right along side of it I would offer french toast as well..(eggy bread in some countries)...it is a familiar sight and texture, but would have the extra protein. Will she pick at dry cereal like cheerios? Offer that with her fruit...just put it there, don't talk about it, or sing-song her about it, just put it down for her, and whenever possible, sit next to her and eat also. Too often we Mommies put the food down and then go about cleaning the kitchen or what have you....when lo's learn by example, and we should eat and enjoy our food, and conversation that goes with that.
Averages are just averages...nearly everyone falls somewhere above or below...please try to relax about this. Your dd is picking up on the anxiety and the expectation and the pressure...no matter how we try to hide it, they feel it! Food is just for experimentation at this age, and that is just what she is doing.