Do your characters adapt? They ought to. Any tale, regardless of length, is about changes - after all nobody in life stays static so your characters shouldn’t. Your characters should develop as we do in life. It’s in that sense any fiction should mirror life.
Take your time going over your completed work, particularly if it’s a novel. Ensure everything makes sense, that the plot lines tie up and you know what’s happened to all your characters. It’s easy to forget a minor character - if you find this happens, ask yourself if you need them in your story after all.
Do read a wide variety of self-help creative writing books. Yes, they have a lot in common (confirms good advice when you read it) but each can inspire and encourage you in different ways. It gives a wide range of perspectives for you to consider too.
Are you enjoying your writing because if you don’t nobody will? Are you committed to writing regardless of whether you get published or not? Are you willing to write, rewrite and keep doing so until your story is right?
Can you answer questions about the world and characters you’ve created? Can you imagine them living on after the novel/short story you’ve written? Do they seem as real to you as the real world out there? No. It’s not a sign of insanity but a sign you’ve thought your world out properly.
Does your society have rules? The answer should be yes. Even a society seemingly based on anarchy will have someone in control of it all. Do your rules work? What happens when these are broken?
Ask questions about your tales like:-
How are your characters’ basic needs met?
What is the hierarchy (and there has to be at least one, someone has to be top dog)?
How is your world governed? Are there rules nobody can break? What are the reasons?
In dealing with magic, can everybody produce the same amount? Or do certain groups have more magic than others? Can those lower down the scale “earn” or “learn” more magic to bring them closer to their superiors?
What happens if someone defies the basic rules or some lowly herbert betters themselves magically so they become superior? What would the fall out be?
What happens if someone from the superior class magically speaking rebels against that or the structures of your society?
There are loads of stories to be found in answering these.