I think there's a couple things at work holding you back here.
I'd say for you, keep working on your fundamentals (anatomy, value, composition, perspective)
Keep on doing life drawings and always do photo studies, that is the fastest way to get better. Dont just copy stuff either, when you draw something from a study, put them next to each other and ask yourself what you did wrong, and try it again. There are no shortcuts.
I know you want to go and carve out your own style and niche in this world, but you need to master the fundamentals before you can warp them.
With this knowledge, you'll also start to develop a latent understanding pleasing design, that'll make your designs feel so much more alive.
Keep up the practice, though, we're all gonna make it!