I’m an author but am concerned about my story

I’m a young author currently seeking a publisher. I adore my world, story, and characters, but I’ve been doubting my prose and skill recently. Is there any way to determine if my plot and subplots meet expectations for readers, and if my world-building/characterization is engaging enough?

I’ve been crafting this universe for years. I’m concerned I may have stared at it so long I’m unable to find gaps and flaws a reader might notice. Pointers?