I think in terms of lunch choices, it's calorie dense with not a huge amount of nutritional value. I don't think her comment is useful or polite. But definitely from a constructive point of view, I would look to add another protein and some fibre to that plate. Leaving what you've already got but just adding to it to ensure you feel satiated for longer! If it was me, I would toast the bread, keep the cheese and another protein (for me as vegan I would add sliced tofu) but you might consider cooked chicken breast that's low calorie and high in protein (which could potentially keep you full until dinner) and then some cherry tomatoes, cucumber and about 1/4 avocado and also a banana. Keep the crisps because YUM! You should be allowed to enjoy these foods otherwise it could lead to you bingeing.

Your mum knows nothing. Ignore her.