Whoa baby!

Amber Rose is counting down the weeks 'til the arrival of her little one with fiance Wiz Khalifa. In the meantime, her belly is getting bigger by the day.

The pregnant model, 28, took to Twitter Sunday to show off her rounder-than-ever tummy as she nears the end of her second trimester.

"As promised . . . 21 weeks," Rose captioned the self-portrait, in which she's rolled up her black tank-top to expose her bare belly.

Rose, who dated Kanye West prior to meeting the "Black and Yellow" rapper, 25, first confirmed her pregnancy at the 2012 MTV Video Music Awards with her man by her side.

"We're expecting a beautiful little baby, me and Amber. We're so excited," Khalifa told MTV News' Sway Calloway.

Rose also got personal on the red carpet at the MTV Movie Awards in June, gushing to Us Weekly that she loves "everything" about her fiance -- whom she says she met on Twitter!

"That's my baby. He is my little angel. I love him," she shared. At the time, Khalifa said he "absolutely" wanted to start a family with Rose.

Joked his bride-to-be, "He wants 12 kids!"