An orphan developing strange powers is unaware that an alien force needs to destroy her if they are to succeed in invading Earth

Make your protagonist active!! Right now you have the orphan in a fairly passive spot. The story should be about what she has to do in order to overcome danger

While the concept sounds interesting...

In the logline, you need to tell us what the lead character must do, because, in your logline, things happen to the lead character but the lead does not have a pro-active goal.
So I would look at your story and figure out what the lead character's pro-active goal is and add it to the logline.

The logline sets up a? situation for a plot.? Now it needs to follow through with the plot that results from the situation.?What must the orphan do about the jeopardy she will eventually realize she is in?? As the designated protagonist what becomes her objective goal?

Just testing a new version of my logline for a feature script.