I have very much enjoyed reading your journey here. As a fiction author (fantasy, YA), I've found that series are critical. I've seen a decent uptick in stats after releasing the third book in my recent series. Amazon had a series page up for me in a couple weeks but I was thrilled that they were upfront and supportive through the process.
I've also started a pen name for short story romances (not erotica) and I've found some success there with a similar strategy to yours. I don't advertise those but I have been doing Amazon ads for my other work.
I am fascinated at the speed of your production. I think I remember in a past article you shared that these short stories are around 5K words. Great job. I'm looking forward to hearing more about your journey.