I do know about the calcium, you need 3 serves of calcium per day - otherwise take a calcium supplement. As for iron - supplements are only recommended if you are anemic - which is very individual to the person. You should also have your dr test you to make sure you are not vitamin D deficient - this can't be rectified by food but easily can with a vitamin. If you are taking prenatal vitamins, you have covered your folate. You should also check to make sure your prenatal contains iodine which is important - I know Blackmore's has it. I don't think Elevit does.

I am sure if you google, there are sites with detailed info on what you "must" have for a single, twin and triplet pregnancy (I've seen them in the past). They will cover protein serves (and sizes), fruit, veggies, etc. I think if you are eating healthy and small portions every few hours you will probably find that you are doing pretty well in terms of eating the recommended serves.