While this species and other succulents like crassula are often mentioned as good options for notherners because they can technically come inside, the caveat is that they're at a virtual standstill when they are indoors (esp. for development purposes). Northern summer heat is also short-lived, so in comparison to someone growing in a succulent-friendly climate, the plant is developing on a much, much slower timeline (for everything: growth, recovery after operations, etc).
Lack of light and lack of ambient heat are your main challenge growing p. afra in Michigan (as opposed to fertilizer). To put it another way, you could grow a p. afra the size of a school bus using zero fertilizer as long as you had enough sustained heat and sun. Its consumption of water goes hand-in-hand with the application of light and heat, so another way to interpret the "overwatering" comments you have received elsewhere is "underlighting/underheating". You could water a p. afra much more frequently if you had it in very hot, very bright conditions and in a drain-happy, oxygen-rich medium. If it's sipping water quickly, then it's adding mass quickly.
Since you are not in Florida, SoCal, Corpus Christi, etc, this species is going to grow very slowly unless you envelop it in heat and intense light, and this is true whether you have a big container or not, or whether you give it a strong fertilizer or not. Fertilizer can only extend and enhance the growth that's already happening, after all. I have a 280 day growing season with hot dry summers and very strong winter grow lights and still struggle to match even a fraction of the momentum that a p. afra or other succulent attains effortlessly when left unattended on a porch in suburban San Diego. It may be time for a mini grow tent or a bit of a re-think re: zone envy!
