Toddler won’t eat

My almost 18 month old is so picky! He will throw his food on the floor immediately before even trying it first, it’s really stressing me out because he’s literally only eating fruit, eggs, apple sauce and yogurt. He will only eat Mac and cheese for dinner it seems but I refuse to give it to him that often because it’s not healthy. The apple sauce has a serving of veggies but still. I can’t afford to make him a new dish every time he throws it on the floor so I tell him he doesn’t have to eat it but I will not be giving him anything else. He definitely understands me when I say that but it doesn’t always help. What do I do??