04/21/2012 AT 01:15 PM EDT
is still expecting.
The mom-to-be, who celebrated her "dream" baby shower
in March, is setting the record straight about the arrival of her first child.
"To everyone who keeps congratulating me on the birth of my baby girl," she Tweeted Saturday
, "I'm still pregnant!! Don't believe what you read ladies and gents."
Simpson recently played bridesmaid
at a pal's wedding, which she attended with fiancé Eric Johnson.
"Jessica looked stunning," a source told PEOPLE of the event. "She was moving very slowly and Eric held on to her tightly so she wouldn't trip in her shoes."
(The star, 31, has said she's "waddling" but still wearing high heels
Added an eyewitness at her friend's nuptials, "It was difficult for her to get around, but she was a great sport and kept smiling."
And she's kept her sense of humor