White Mage has 28 actions. Add in 5 cross class skills and you have 33. With expanded cross hotbar, you have 32 slots. To fit everything, you only need relegate one of your abilities to a 3rd crosshotbar (Stoneskin 2). If you don't have enough space, that is because you have unnecessary things taking up prime space.

There are much better methods of saving space than putting tetra and cure 2 together. A lot of people have various Stone spells sharing one button via macro. Protect can be placed on the 3rd hotbar along with Stoneskin 2. Swiftcast and Raise can be combined on macro and still be fully functional (unless you want a raise announcement macro). Again, you shouldn't need any of those. Once you move Stoneskin 2 off your 32, you should have enough space.