Hi Kelly
I really don't have any advice as William is a food monster. I just wanted to give you a cyber hug as I can imagine how stressful it must be to have your little one losing weight. I would go by what Lucy said and stop worrying so much about the solids and make sure she is getting plenty of the boobies that she seems to love so much.
Isn't your paed appointment next week?
BIG BIG hugs
Sarah