OP my eldest 25, she was a fantastic eater, my middle one is 'ok' and my youngest (5) was awful - she has got much better and will actually veg at meal times now but no meat. Her go to meal at the moment is plain pasta with butter, raw carrot, cucumber and broccoli. This is a vast vast improvement on when she was three.
Breakfast was a nightmare for me to just get her to eat something before school as her teacher was telling me she was hungry at school and they were giving her secret biscuits
She was only eating the bread rolls at lunch time too...
When they are small food is the only thing they have control over. I never force food or make them feel like they have done something bad by not eating. They never get punished for not eating. They never get left to go hungry - ever.
My dd has a sweet tooth and would gladly eat chocolate for breakfast every day as in a spoonful of Nutella and a hand full of strawberries. A habit that derived from Nutella on toast on a Sunday until she scrapped the toast ( very cleverly bu asking for the Nutella on this side as she wanted to read it on
and just wanted the Nutella. We are now at a croissant and strawberries.
I would give your ds a bowl full of berries/fruit to go with yogurt and toast. Thats a good breakfast any way.
Try soups like cauliflower soup as its white and creamy with a very mild taste.( my dd calls it white soup) as if she thinks cauliflower is in it she won't eat it) I put a bit of grated cheddar cheese in it for fat and serve it with a warm roll and butter. that goes down a treat.
Try really plain pasta and butter. with a few raw sweet veggies. Make a face out of the veggies.
And finish up with toast and yogurt/milk for supper.
Cut out snacks.
Dont make it a battle, they have only been on this earth 3 years, their taste buds are different to ours.