Frazzled, what would you do to replace the steaks etc on that diet. Do you eat quorn?
Willa, you probably do need some advice from a professional dietician. Protein is almost definitely the way to go, but proteins containing good fats, so perhaps those from vegetarian sources, such as quorn, avocado, nuts and seeds? Eggs are good for breakfast, as is full fat natural yoghurt - actually the best breakfast is probably porridge, as although its not high in protein, its a slow release low GI carb that really fills you up. If you add a good amount of fruit to it as well it will really keep your blood sugars stable for quite a long time. For the rest of the day you really need to keep your protein levels up to stop the crash that makes you crave the sugar, a handful of nuts or a small chunk of cheese as a snack between meals can do that.
I was had an eating disorder myself when I was younger (I was a food restricter) it did recover, but it seems that once I started eating sugary food again I had no self control around it, so its been an uphill battle ever since really.