Glad its not just me then

But the thing is if she came home for lunch she would eat like a horse, she just worries about it (despite countless talks, meetings with teachers).

Definitely a common problem. My kids are both the same. My daughter has taken a liking to soup, so she takes a flask of soup and some bread and butter every day. If your daughter doesn't like bread perhaps she could have some soup with pasta in it? I spend half my life worrying about my kids starving at school

In the past I have given mine pots of salad (in the little take away containers) and cold pasta they like things like that. i'm ok atm as they like to have the hot school dinners in the winter months.