Can you give better examples of what her day to day diet is, not an out of routine day list. Also full details and what you consider “small” and what included in the meal, a bowl of rice with fish/meat or anything else in it is not the same as a small bowl of rice.
I was overweight as a child, hit when I was 9 I never heard the end of it from my mother and have weight issues now, I comfort eat, eat when bored and eat all the wrong things. The saddest thing is, when I look back on the very few pictures of me back then I wasn’t that bad but I thought I was because my mother told me I was.
I think the biggest issue you have is her fitness, I’d be trying to introduce more exercise that dose not feel like exercise. Family walks, older siblings maybe asking her to go for a walk. Build up her stamina before introducing more exercise. Dose she have a pedometer, could you get her one and try and get her into step challenges.
It may be that your daughter is just going to be big regardless. One of my best friends is big but is far fitter and dose more exercise than a lot of skinny people I know. Same with my DN, she’s always been big, huge appetite, when little could out eat most adults, but is very fit and sporty, she’s shot up in height the last couple of years so her weight dosnt look as obvious as it once did, it also helps with her sports.
Your also blaming your 9yo child for the rest of you not being able to have treats, do you understand how that sounds? You do also realise how much resentment that will cause in your house.
Lastly, I think you need to look at some of your house rules. None of my DDs would ever help themselves to food without asking and if we say no, it’s no. We buy the food for the house, once my DDs start buying their own food they can help themselves, but until then they ask if it’s ok first and respect our decision when we say no.