DESIGNERS : Turning Up the Volume : Dresses: Nicole Miller’s loud prints and hip shapes are just what working women ordered--by the dozen.

New York designer Nicole Miller is suddenly the darling of fashion critics (“It’s fasten-your-seatbelts time . . .” began a recent review in Women’s Wear Daily), the subject of a People magazine profile and the namesake of a fashion company whose dress and sportswear sales hit $28 million last year, up $6 million over 1989.

Why the gush?

Dresses.

Since going into business for herself eight years ago, Miller has never turned her back on them. Now, she contends that even more women find sportswear separates too complicated.

“If you don’t buy all the components--and women are such impulse buyers, they rarely do--you have tons of different items in your closets and it’s impossible to get dressed in the morning,” Miller noted during a recent stop at I. Magnin, Beverly Hills, which carries her label. “Especially if you’re one of those people like me who waits to the last possible minute to get up and go to work.”

Miller’s dresses, which range in price from $250 to $500, are hipper than ever. On the conservative side, she offers short double-breasted coat dresses to wear alone or over leggings. She expresses her quirky side with amusing silk prints--oversize Sweet ‘N Low packages and matchbook covers from New York, San Francisco and L.A. restaurants--sewn into fitted A-line shapes.

Her success is no mystery to her. “It gets down to my personal life,” she said. “I spent four years in a crummy relationship being depressed. I had a boyfriend who was restricting my life. I’d run home and cook dinner,” says Miller. Now, “I go to parties. I entertain. I got back to being myself again.”