My DS2 was extremely fussy, he only ate some meats and pasta for main meals. He did have yoghurt and lots of fruit and what I call plastic cheese.
I gave up on dinner, eventually once he turned 4.5 I started the "once you start school, you have to start eating....", it worked. I would start with tiny bits of broccoli and cauliflour and carrot and he would taste. We are now at the point (6-7mths on) he actually likes them and eats more.
It's baby steps. They eat what they eat.
It's a case of choose your battles and this one I decided not to battle on