If i go on a low low calorie diet while i breast feed, is my baby not going to get enough vitamins?

Maybe but maybe not: If you restrict calories but still maintain a balanced diet, your baby will be fine. Reduce the sugars you take in but not the fruits and vegetables. Be sure to keep on water though. If you are dehydrated at all you will make less milk. But calories doesn't equal vitamins. Good luck!

Not enough calories: Your body needs to take in enough calories to produce adequate breast milk. If you reduce your calories too much, over exercise, or not take in enough fluids, your milk production will drop off. What breast milk you make will be nutritious, it is the quantity that can suffer. Most women will lose weight naturally with breast feeding. Eat healthy, with good sources of protein, fruit and veges.