My first language is English but I'm studying the Romance languages. I think English gets a lot harder when you add local venicular and slang into the mix. It's already a melting pot language but when you add newer slang like tots, sus, gucci, yeet -- it gets WAY more confusing.
Regarding writing - I actually don't think it's excruciating. I DID feel that way before I found my writing style. For example, dialogue. I think you can "edit" the heart out of dialogue and it goes from a character's unique voice and into a generic sentence.
Its a infuriating hobby, especially when you compare to professionally done novels.
Like @diamondpowder said - don't compare yourself to "professional" novels. I'm sure a lot of us have seen the Tumblr post about Twillight that had the line "Aro laughed. 'Ha ha ha,' he giggled." That line is redundant to a T. And yet that line slipped by Stephanie Meyer, her editors, proof-readers, etc. I've read Marvel fanfiction that had more heart and was more dramatically gripping than a lot of commercially published YA fiction I've read. It just takes time to develop your skills and eventually you will find your audience. I would rather write something I'm passionate about that fits into the "Cherry Stark style" than something generic.