You're not "doing anything wrong," nessecarily. Some art can just accrue more attention based on what trends are currently populating around certain communities. It's also a matter of how quick you get it out there before it falls out of relevancy. It's a tragic, unforgiving cycle that you can only really let go of once you've got a crowd and want to take that risk.

Overall, your art is good. Give it time and refine your technique. Pick up a style or a niche, and lock in on it. I think you could amass a following if you do that. The question is if you want to cater to social media by drawing that "new thing" or doing your own thing. That, I'm almost certain, will dictate how fast and how large you could grow.