The TOWIE star, 24, shared a couple of snaps of herself this week looking fit and trim, showing that she's already got her teeny waist back.
Her followers on Instagram shared out surprise at her bouncing back to her pre-pregnancy figure so quickly.
One user wrote: "How do you look like that?! I gave birth two weeks ago and still look pregnant", while another simply commented: "You look amazing!"
SEE: BABY NELLY SHARES A CUDDLE WITH DAD GREG SHEPHERD
This week Billie spoke out about her first month with baby daughter Nelly, and she praised 27-year-old broker Greg's parenting abilities.
She told a British magazine: "Nelly is inquisitive and always looking at things and people. She's going to be a real character.
"Greg's taken to fatherhood much better than I expected and I'm really happy with him."
Billie recently revealed that she and Greg decided to have Samantha for Nelly's middle name, in a tribute to her sister.
PICTURES: NEW PARENTS BILLIE FAIERS AND GREG SHEPHERD LEAVE BABY GIRL AT HOME TO SPOIL HER IN MOTHERCARE
She said: "We thought it would be really nice for her to have Samantha as her muffle name because Samantha was there when she was born.
"I started crying as I was telling her and then Samantha started crying."