Can't find the pet tab.

I'm currently at level 23, and I'm looking in the spell book, and I can't find the pet tab. Nor, can I see the pet bar/pet action bar. Which both are enabled on screen. Am I missing a setting here, that has to be enabled?

I tried googling it, and couldn't find any reasonable results that would explain this. I seen that other people had a similar issue, but I only see three tabs at the bottom of the page: Specialization, Talents, and Spellbook.