Honestly there is nothing wrong with writing about gore and horror! Many people make a lot of money by doing so,, and it IS what you enjoy doing. I'm also a huge fan of horror stories and I've been trying to write some myself! So far Junji Ito,, Danganronpa,, Corpse Party,, and a few others have been my biggest inspirations. I Believe that you should go through with writing however much you can,, do what you love! If you can't use your school account start off by writing everything in a notebook. Go in and plan out each idea you have and go into detail about how you want it done,, so that whenever you're able to actually write them you have a solid idea. I believe in you! Don't let anyone change your mind on what you want to write about.
If you would like to talk more about any of this I have discord,, my ID is pulchra#6660 if you wanna add me! If not that's okay :D