I think not dieting is the key. 96% of diets don't work, it is very difficult to come off a diet and not put back on all the weight and more.
I think you need to make the decision to give up buying junk and only have in healthier food. Don't go mad, don't go hungry, but short term fixes don't work. Starting having brown rather than white bread, pasta and rice is a good place to start.
Though I have to confess I have never been on a diet and am quite small. I did develop a bit of a chocolate habit after dd was born. When I started gaining more rather than losing baby weight I had to stop having chocolate in the house at all times. Its a once a fortnight treat.
I was eating a lot better when we were getting vegie boxes and cooking from scratch.