Thank you so much for all of your replies. I'm overwhelmed by the responses, and grateful to those who have offered genuine advice/tips (which I've screenshot and will look into). It's unfortunate that there are still a few that have either not fully read the OP, or are telling me that it is as simple as reducing calories/portion size, or that I'm enabling - I do realise this. But there has been more kindness, so thank you.
To answer a few questions and give some more background...
I have three children, she is the middle child. The two boys are healthy weights. The eldest is very health conscious and regulates his weight well. The youngest is slim, but has ASD and is fussy to the extent that he only eats certain foods and not very much of it - so a whole other issue I'm dealing with.
8 years ago, we fled my from my ex, their dad, and I put all of my energy, money and what little mental strength I had into starting a new life for us and somewhere new to live. We live in a run down estate in a less than desirable part of London. We don't have a garden, or friendly neighbour's who would want their dog walked, and we couldn't afford a dog of our own, nor would we have the space.
A lot of my daughter's mental health I believe, stems from her relationship with her dad, and the horrible environment we lived in where we would all walk on eggshells. There was no physical violence, just emotional. I finally had the courage to leave, and in many ways, life is better for us all. I did plead with social workers in the early days for involvement, and to my surprise, they said I didn't qualify as in their eyes, the children still have one fit and able parent.
The boys are thriving now (although they've had their problems with mental health in the early days), but my daughter keeps a lot in. I too have struggled, which I guess is a reason I've not been able to effectively get a grip on my daughter's weight.
My daughter has no friends, and has endured bullying since primary school. She has no one to go places with, and this adds to her MH problems. She has no confidence to join free afterschool clubs, and is definitely a few years younger mentally and struggles to fit it. Obviously I've tried to address this, and have tried to help, but I think its deep rooted and will take a professional to unpick.
My daughter is in denial about her weight. I know she knows, but she won't admit it, which makes it very difficult then, for me to get her on board. She will say things like "ah mum you've shrunk my clothes again" or, "I need a bigger size as I'm getting taller".
I've taken her to the GP who recommended Slimming World. We attended for a couple of months, but on the times she gained or stayed the same, she would be heartbroken and have meltdowns. I decided I didnt want to fixate on weighing her, and the group was just making her feel more of a failure when she would see the other people achieving awards etc.
She does eat veg, and fruit, but just never seems full. So even if her plate consisted of mostly vegetables and proteins, she would still be hungry.
I'm thinking if I can make her as comfortable as possible, then I may be able to convince her to get more active. Is there anywhere I can get specialist shoes made? She has wide feet, a high in step and obviously a lot of weight bearing down on her. I've tried sketchers etc, but her feet always hurt in the end. I will definitely look at the anti chafing shorts - so thank you.
I understand diet is key, but I also know how good I feel after being active, and I want her to get that feeling, in hope it will make her want to make better food choices. I also need to work on keeping the momentum going and not cave when trying to get her to eat less junk.
It might be worth noting, that her weight gain increased a lot over the lockdown period. She was still very overweight before, but gained rapidly over the lockdown period.