Been making my own deodorant for about 3 years now. I started with a coconut oil-based recipe kind of like the OP's, but I left out the shea butter. Protip: adding cornstarch makes it more pasty, so use more in the summer months. In the wintertime, I left it out entirely.
These days, I don't even bother with the coconut oil. Mixing the stuff is annoying and messy and leaves a whole bunch of unnecessary residue in your pits (and on your shirts). Currently, I have a repurposed powderpuff compact filled with baking soda, which I use to powder my pits. A few drops of almond oil (or whatever oil you have handy) before powdering helps the powder stick. Works just as well and conveniently without the extra steps of mixing stuff, and you save the expense of coconut oil, which is fucking precious if you haven't noticed.