Welcome, and I like this shot because of your unselfconsciousness;
you seem to not notice the camera at all. In most
self-portraits the subject usually appears quite
aware of the camera. It's not easy to forget about the
camera, especially when you're the one operating it. I
would never have thought that it was a self-portrait if you
hadn't said so. Nicely done.

As far as what it's missing is concerned, that's hard to
say. What do you think is missing? What would you add to
the scene if you could choose from anything? It all depends
on what you would like, not what others would like. (And
yeah, composition of a scene is one of the hardest things
to decide on, for me, and I think that's where a large part
of the art in photography lies.)