Agree with everything Laura said.
Just wanted to add, if you are really concerned about low veg intake maybe try giving veg at breakfast or lunch (or snack) instead of waiting for dinner. Slightly different but my LO wasn't eating protein and by dinner it was kind of a case of me pinning my hopes on him having a bite of something protein, it wasn't the right time of day to offer a food group that wasn't his favourite and was too late in the day for me to have any further opportunity to get him to eat some. I changed to making breakfast a protein meal (which he eats without question, clears his plate and thoroughly enjoys!) and basically means if he only eats veg and carbs for dinner it's fine.
Frozen peas, canned sweetcorn, batons of sweet pepper, carrot, celery make nice snack food so LO gets the taste for veg in it's true state rather than in burger form, even if he doesn't eat much at all with the family (but like Laura said, cutting down on snacks can also lead to better appetite for the evening meal).