There is no escaping this, so you might as well accept it now. If you turn away from your creative gift, it will not go away. It will just fester, and you will become depressed.
You may have a modest gift. Still, it is a gift. It is not yours; it is entrusted to you. It is something beyond you, something you didn't cause to come into being, but something that was handed to you. It is a gift, and with it comes a duty. Carry it lightly, but carry it.
I don't believe you are ever wasting your own time by writing. Some people might think you are wasting theirs, but that's their problem.