Edge of the Barrier (The Barrier Series, Book 1)

Anne Blankenship has only seen blurry photographs and rough sketches of the aliens that destroyed the world. All she knows is that one day, they invaded Earth, and then the next, NewMerica was forced to live within a force field to protect its people from the creatures.
But for Anne, that happened over a thousand years ago, and all she cares about now is passing her career test and becoming a doctor. But the announcement of "The Royal Lottery" and a chance to meet the prince cause chaos all around her. Little does Anne know that these events will lead her to break both physical and social barriers alike.