Is it okay to diet while on the protocals? I know I shouldn't when pumping, but was curious if this was okay.

Dieting can definitely mess up hormone levels, depending on how it's done. Being too thin can really mess up your hormone levels.... Then again, being significantly overweight or obese can definitely mess up your fertility and probably also your milk production as well because it also interferes with proper hormone and other bodily balances.
You should check with Lenore, your lactation consultant and physician about this in my humble opinion!