Hi Audrie, and welcome!
Wow, those are some fat and happy stapelias. I would say that a commercial cactus/ palm mix would be good, maybe even a little more pumice to add in the drainage. I'm familiar with your brand of sun, being also in the SW. We can grow these outside here, but they need at least dappled or filtered shade, perhaps morning/ eastern sun. But without enough sun, yeah, the blooms won't appear. When you put them outside, you'll want to slowly acclimate them over a period of a couple of weeks. You might want to stick a fluorescent or LED light over it while inside, too.
If you look at Tee's original picture, one page back, you can see what they look like when they're grown with a little more sun and a little less water - if you move yours outside, that's likely what it will look like, just to forewarn you of changes, so you don't panic! It will be perfectly healthy at that point.
