K.,
Calmness. It happens to lots of children (and parents!) My son is a 'grazer' too. There are days when I can get breakfast in him and that's it for the rest of the day! There are days when he will walk around all day with his mouth open like a hungry baby bird! LOL Sheeeeesh, and don't get me started on trying to get fruits and veggies in him. That takes an Act of Congress in itself!
If you little girl starts losing weight (more than a pound or two), consult your pediatrician immediately. Consult your pediatrician on using suppliments like vitamins and "PediaSure." Be careful about giving her foods that have higher allergic reactions....such as peanut butter and eggs. Wait until she is 2 years or older to offer these foods to lower any risk of developing a food allergy in your lil one.
One tip I use regularly is a cookbook called, "The Sneaky Chef." This cookbook teaches you how to add fruits and veggies into dishes - so when your lil one DOES decide to eat....at least you know its something healthier than a chicken nugget or a french fry.
Best of luck and hang in there.