Allow me to offer some words of encouragement, just like how there are no more unexplored lands left on earth there are no more untold stories due to the many millennia of the written word.
All stories can be divided into three groups Man vs Man, Man vs Nature, Man vs Myth.
There is no shame in your story being similar to someone else's so long as it came from your heart, do not be ashamed to tell your story just because others exist.
After all, would you refuse to go see the grand canyon for yourself just because someone else has already seen it?