02/06/2013 at 12:35 PM EST
was about to experience a dream moment for any bride: trying on wedding dresses at Vera Wang's chiffon-and champagne-filled boutique in West Hollywood on Feb. 1.
"I was in the changing room, and I looked at my armpits, and I was like, 'Are you kidding me? I look like a cave woman!' " recounts the singer
, relaxing a day later in jeans and a hoodie-covered Willie Nelson T-shirt in her adopted hometown of Nashville.
"And then I took my pants off, and I was like, 'Oh my God, my legs match!' My nails
looked like a hot mess; my eyebrows looked like bushes. I was so
not a girl. I started tearing up because I'm like, 'This is not me. I'm usually not this gross. I'm just so busy!'
"And then on top of that," Clarkson continues, "My friend got incredibly ill like in the movie Bridesmaids
. She's like, 'We are totally not going to get asked back here.' "
So things didn't quite go as planned
at Vera Wang, but by day's end, the bride-to-be did score the dress of her dreams. And a Grammy dress
. And even a Jane Austen-inspired frock for an upcoming family portrait. (More on that in a bit.)
The wedding gown "is my personality in a dress," she says. "It's sweetly damaged. A little rock and roll. A little tattered. Nothing like a princess thing!"