I think your problem is this:
done a whole load of diets, weight watchers, slimming world and all the rest
The problem with a diet is that it's a temporary thing and always has to stop. Your underlying "normal" way of eating doesn't change, so when you stop the diet you're always going to put the weight back on.
My sister does this. She'll successfully lose weight for a wedding, a holiday or whatever, and then stop - and go back to her "normal" of large portions, snacks and puddings. Then the whole process repeats a few months later.
What you need to do is stop thinking of a diet, and stop thinking about aiming to lose weight. That may sound trite but honestly, it worked for me, and (bar pregnancy) I've never put any weight back on.
Instead, thinking about eating healthily, forever, and eating how slim people eat - starting today. If you eat like a slim and healthy person, you will become a slim and healthy person. You need to create a new "normal."
That means nothing is completely off limits forever, but day to day you won't be eating any ready meals, nothing pre-prepared, nothing that says "diet" or "low fat" on it - just veg, fruit, meat, full fat dairy, the odd bit of wholemeal bread and pasta. Proper food, basically.
Since we adopted the "no crap food, just healthy food" approach four or five years ago, we never go down the biscuit/cake/crisps aisles in the supermarket, so this stuff is never in the house. That helps DH as he is easily tempted!
Nothing is "banned" for us, but desserts are maybe once a month, and only really if we go out to eat. Alcohol might be the odd glass of good wine. Fast food - rarely or never. But if we have a dessert, we enjoy it and go for a decent cheesecake or something, not a sad WW yoghurt.
Eating like this means I never feel like I'm depriving myself as I can eat whatever I like, I just have to balance it out over the week.
It becomes habit and then normal, and before you know it, eating a biscuit would never occur to you. Because there aren't any biscuits in the house, and that sort of stuff is no longer part of your everyday diet, it's just not a consideration.
Whereas my sister, for example, will have a "bad" day where she eats a biscuit and feels guilty. Then she eats a load of biscuits, feel she's "cheated", then gives up and eat crap for several more days. Until the diet starts again.
At the moment you sound like you're in a cycle that's making you really unhappy. You need to break that cycle and say from now on,no diets, just healthy food for the whole family, forever. Forget weight, think of it as being about health. The scales will follow in time.
Being slim isn't an accident that happens to some people, it's a byproduct of eating well over a long period of time. It doesn't "start" and "end" like a diet does. It's not about deprivation.
It must be frustrating that you can't exercise at the moment, but size is mainly down to food consumed anyway. If you start the healthy eating now then exercise can follow in time.
Sorry for the lengthy post - I hope that makes some sense! Just wanted to give another perspective. Good luck.