The fifth-season American Idol finalist got engaged on a Florida beach on June 15, a day she says had been "sad and hard," because it was the birthday of her late grandmother, Faye Pickler.
"It turned out to be the most amazing day of my life," the 23-year-old tells the magazine. "My whole world changed. We both feel like we got my grandmother's blessing."
The couple met two-and-a-half years ago.