This eating malarky is ALL in the mind. Firstly, well done in getting to a healthy weight for you.
You should never 'diet' - that thought will just make you want to eat lots of 'forbidden' things.
The secret is to now tell yourself you are going to be good to yourself by only putting all the good stuff into your body.
You have done so well, why on earth would you want to do damage to yourself by scoffing fats, sugars and all that sort of crapola into your body. Your thinking now should be just to eat healthy.
You can graze all day on good stuff without feeling hungry or putting on weight.
If choccie, for example is your thing, then never deprive yourself of it. Just have some occasionally inbetween all the fruits, veggies, fish, good stuff etc.
So you wouldn't want to 'go back' to your old habits, as you put it, as that would be unhealthy and make you put on weight. You've now learnt how to eat healthy and, believe me this will just become a part of your life. It won't stop you doing anything. For example, if you eat out, just have dressings on the side, and have things cooked without fat or butter where poss. It's so easy to eat well these days.
Don't think low-carb, Atkins or whatever when you're thinking long term. Just think low fat, healthy stuff (fruit, veggies, fish, white meat, nuts, wholemeal bread, etc etc) with the occasional bit of whatever you fancy.
Hope that was of some help. x