I think some of what you are seeing is a simple issue of supply and demand. The community that has this kink is relatively small compared to being a general model and with quite a few models vying for the same small pool of people and money it has to be hard to consistently make money.
The rates you charge are very reasonable and your videos are well made. I don't think it has anything to do with you it is just the nature of the beast of being a fetish model you have to work twice as hard for half the reward of a regular model.
I have bought a handful of your videos but, I have many other interests etc... and, with Covid still a thing and the economy not exactly on sure footing I am saving more. I think many people are in the same situation or worse.
I can totally understand your frustration with putting work into something and getting little reward. I have a youtube channel and when I put a video up that I worked on for days and only a few people watch it. It can be very discouraging.
You are one of the best models on the site. I am sure things will get better.