Will having an eating disorder prevent me from getting pregnant or having a healthy baby?

Maybe. Most babies turn out fine in spite of nutritional balance, sometimes there are issues in spite of good nutrition. You are more likely to have problems with nutritional imbalance. Be sure to take prenatal vitamin if you are child-bearing age.
Maybe. A restrictive disorder, such as anorexia nervosa can cause loss of body fat to the point where it affects hormone levels and may prevent pregnancy. As far as having a healthy baby, it is essential to have adequate nutrition intake.