I still think it's hilarious that you have exactly ONE healing option when you first start this game. You need to be level 30 before any other option opens up. And that's never going to change, thanks to the policy of having new jobs start at elevated levels.

As folks have said, a new healer doesn't need a new category (shields, regens, both). They can join an existing category, and simply do it in a different "style". There's no need to balance existing healers first; just make sure the new job is balanced to whatever healing category it joins, and when you DO balance the healers, balance it in the same way as the other in its category.