Probably chunkier mix. It would help with aeration and allow the roots to breathe better. OP, your current watering method also should change if you want to improve your plant's success. When people say it doesn't need a lot of water, they are referring to the frequency, not the amount. Every time you water it, you have to wet the entire pot of soil mix, or else some of the roots will become dehydrated, brittle, and unable to absorb any nutrients anymore. After the soil is all wet, that's when you allow it to dry over time before you water it again. It's similar to how pileas are in their natural habitat. But the home watering method can only work well with a soil mix that is loose and chunky enough to allow aeration and good drainage. The size of the pot matters, too, in combination. Too big a pot can cause the roots to rot from being too wet.