No, you're not good at writing.
You're BLOODY AMAZING at it! Your work surpasses the expectations most publishers seek in an author! I would KILL to be as good as you. Don't put yourself down like that.
Maybe people aren't interested on the subjects in which you write. Many writers struggle with his/her readers not sharing the same interests in books and such. Maybe if you send your work in a different direction, more people would enjoy your poems, short stories, etc.