It's good to recall the life and work of author Ray Bradbury (who died yesterday at the age of 91) when you fall into the but-I-only-write trap.
But I only write . . . science fiction. Fantasy. Westerns. Romance. Short stories. Poems. Mysteries. And on and on and on.
When it comes to writing, when it comes to your writing, there is no "I only."
Writing is writing. No matter the genre.
I highly suspect those who write so well in one form wish they could write as well in another. The mystery writer would like to pen a fantasy. The fantasy writer wishes she could do a literary novel. The literary novelist would dearly love it if as many people read his work as looked forward to the next children's book about a wizard boy in England.
Writing isn't a one-genre-fits-all talent. The gift you've been given, and are nurturing and strengthening, is uniquely your own, just as that developing (or developed) voice is.
Little Willie and I talk about that in this clip.
Just keep writing.