My daughter is M., also, but we shorten it to Jorie. :)
Anyway, she will be 7 the beginning of October, and weighs 37 lbs. She is the worst when it comes to eating! She's usually "not hungry" and is so darn SLOW when she does eat. Drives me nuts.
However, since this has been going on most of her life, I have resigned myself to just keeping the snack shelves in the fridge filled with healthy snacks and whenever the kiddos (my 10 yo son is 53 lbs) are hungry, they are allowed to help themselves. If it's healthy, I don't care how close to dinner time it is. I mean, seriously, what's the difference?? They're eating and it's good for them.
Then I just give them a little to eat at meals, and if they don't eat it, I don't have to stress because I know they've eaten something, at least. We just make meal times more about the family being together rather than the eating part.
Children won't starve themselves, so you need not worry about that. And she's too young for it to be anything mental (anorexia or the like)
So, keep providing those healthy snacks, and let her eat however much she wants at meals (but she should still have to sit with the family at the table until you're done). And the suggestion about the smoothies was great. It's a good way to get calories into her, if you're worried about the nutrition end of it.
Take a deep breath - :) - this too shall pass. (Personally, I wish I could be like our daughters! Then I wouldn't weigh 180 lbs!)