Put the image away. Come back to it in months or years. If it still has impact for you then, then it will probably have impact with others as well.
I have some shots that impressed me not in the least when I snapped them, but I later came to appreciate more. I have many more of the opposite (don't we all)
The major issue, I think, is that we experience more of the scene than actually gets recorded on film. It is inevitable. The sounds, the smells, the wind in the hair, whatever! The widest lens cannot capture all those things. The photo can trigger vivid memories of all that for us... but not for others who weren't there. This is perhaps *the* biggest challenge in all photography, in my opinion. It can substantially afflict those of us who really enjoy the details and sensations beyond the frame. I mean, I get very vivid recollections of all senses when I look at a particular neg, but then I have to face the fact that I am probably the only one on the Earth who feels those things when I look at that particular neg :s If you can make a composition that evokes experiences beyond the frame for other viewers, well then congratulations, you have yourself a classic, timeless photograph.