Katy, when I started out I was advised to consider the balance of food groups over a DAY or WEEK not a meal, and the amount of food too. So I wouldn't worry at all if for example breakfast was all carbs and lunch all veg then evening meal just a chunk of protein iyswim. I think on the whole it wouldn't be quite so split up as this but I don't think at this stage you need to balance every individual meal.
Esp when DS just started out, he ate lots but he didn't like a mixture of things, so it would be a plate of just two different veg and he might eat both or just all of one. So long as I didn't offer exactly the same veg every day then across the week a variety would have gone in to balance the various vits and nutrients and give variety of flavour and texture for him to get used to.
hope this helps - it's really hard to make every meal totally balanced.
Even on a spoon hamish likes to investigate it thoroughly!!
Hamish does like his mess eh! At one of the toddler groups I go to there is a messy play wher they have things like baked beans or cooked spaghetti in a massive tub and the LOs play with it, dive in, get covered head to foot. If DS is hungry he just goes over and eats it, if he's not hungry he totally ignores it! He isn't into messy play or messy food at all.