Hey Paula,
Don't feel bad that you're struggling because I am too. I've joined WW about 4 times everytime I've been a lot heavier than the last time. If dieting was easy there would be no fat people! Maybe you just need to give yourself a break from thinking about it for, say, a week or two and cum into it fresh and ready to go. I bet you constantly think of dieting even when you're not 'on it' because I do. Give yourself a break!
Lots of love, Kelly x