It's not that you aren't good, you just need to get better with your art, and what other way to get better than to keep drawing and practicing. people won't sub if the art isn't appealing. If I were you, I won't even sweat about this one because it comes with time.
another thing is, "there is no background", lack of background would deter readers from reading your work.
the color pallet makes no sense. it's random, it's everywhere, confusing. I can't speak on the story because i didn't read it so i'll leave that for someone else to tackle.
some of the panels are zoomed into the character's face but their facial detail is missing?
I will encourage you to study the at of paneling, learn color combinations, and practice background. I'm not saying all this would give you a high sub rate but it least it will be appealing enough for readers to want to give it a try and maybe sub.