I'll share some of my meals, which might help you, or inspire you... I also have a DS aged 3, so try to keep meals similar to what the rest of the family eat, can't be cooking lots of different things.
Breakfasts... various fruit/berries and 0%fat Greek yog, or boiled egg and brown bread soldiers (1 slice) scrambled egg on brown toast, flora light spread. Eggy bread too, using frylight. Measured portion of cereal and milk. All of the above DS will eat with me.
If I eat bread for breakfast, I won't have it for lunch, so will have salad with couple of spoons mixed tinned beans, couple of spoons of cous cous, and either tuna, ham, boiled egg or cheese... tesco do a 50% less fat cheddar, which is actually quite nice! Or, ham/cheese/tuna salad sandwich on brown bread. Cup a soups are quite filling and low calorie too.
Weigh out all your carbs and meat... its surprising on the portion front, which was my biggest downfall..overeating! I have quickly got used to eating less!
Hope that helps, even just a little bit. Good luck, you can do this!