In April, the star visited both Balmain and Azzedine Alaia in France, settling on a dress that has intricate embroidery.
"It looks good. They came and brought it ... I can't say the people," Carey told Entertainment Tonight. "I can't say their names. The fabulous designer house that's amazing."
Carey and Packer, 48, got engaged in New York City in January, just months after taking their relationship public last September. The marriage will be Carey's third – she was wed to music executive Tommy Mottola and Nick Cannon – and also Packer's third.
The star also talked about her upcoming E! documentary series Mariah's Worldon Live!, Monday, revealing that she "break[s] the fourth wall sometimes."
"Because that's just who I am, so I'm just like whatever," Carey admitted.
•Reporting by PETER MIKELBANK