I just wanted to break this down meal by meal. For reference, I'm much more in the tall and broad camp than the teeny tiny one.
For breakfast I eat two slices of toast with Philadelphia, or maybe one toast with a couple of eggs.
This is completely normal and is about what I'd eat for breakfast. My breakfasts are usually a bowl of porridge or cereal, or two slices of toast (just butter), or toast and eggs.
Lunch is a tin of soup, or salmon salad, or a sandwich.
Again, this seems fairly normal. The only thing I'd change is I'd have bread or toast with the soup.
Dinner last night was curry with chicken and veg, one tablespoon of rice and two tablespoons of yogurt. Other evenings I’ve had roast chicken with veg and only one new potato, or chilli with one tablespoon of rice and a tablespoon of sour cream, etc.
Assuming you have a good portion of vegetables and a decent amount of chicken, I don't see a problem with this. It's not a deprived diet. If you're only having a tiny piece of chicken and one broccoli floret, I could understand.
Maybe an apple or a tablespoon of peanut butter for a snack, or a cheese string.
Apart from the spoon of peanut butter (a tablespoon of it must be quite calorific surely), this seems normal.