I would suggest when making your snacks for her to make them in portions, so that you have portion control, ie if she eats a whole bag she's only eating x amount of strawberries. Then if she wants something else, you have her wait 10 minutes and then give her another portion. And have her ask you for the food, don't let her just take anything whenever she wants it. That way you have an idea as to how much she has eaten.
My husband, who has had weight issues all of his life, also will just keep going and going with food if you let him. Over the last couple of years I've been trying to get him to take whichever food he wants and put it on a plate, ie a portion, and then eat it, as opposed to him opening the frig and devouring the entire quantity of something he picked up. He learned to eat as a soothing mechanism growing up in a alcoholic family where his parents were not often available. Also, if they were blitzed, his eating dinner would be opening up the frig as a kid and seeing what was available, because the "grown-ups" were too lit to heaven forbid feed their kids :nonono:
Re her anxiety, with the car accident, of course that's understandable.
And re the doctor's comment, I think the idea is that if she's eating because she's bored, then give her something with no caloric value. With my difficult child, she would often say she was hungry when she wasn't. I would offer her an apple or an orange, she didn't want it, ergo that was the only option so she went without, because if she truly was hungry then she would eat it.
Just fyi, gatorade has tons of sugar in it, you may want to just mix a juice with water instead.
Hope some of this helps :smile: