Hey CartoonChaser!
Drawings aside, I'd like to ask about another technical aspect of your work - is it possible you draw using your wrist rather than your entire arm?
I feel like your drawings could take an entirely new quality if you took a few minutes to re-trace your line art with clean lines prior to coloring. Try drawing with sweeping lines, moving your entire elbow, and have two fingers on ctrl+Z to try again as many times as necessary until you get the line right.
I took 3 minutes to re-trace one of your characters with clean lines, and I do feel this is the next step you could take to bring your work to "pro" level! Scribbly, uncertain lines are really holding your artwork back at the moment. It's okay for sketching, but it would not hurt to give this a try
Cheers