The 24-year-old TOWIE star and her fiancé Greg Shepherd welcomed Nelly July but that hasn't stopped her from getting back into her skinny jeans already.
She told the MailOnline: "My size eight jeans fit me again which I am very pleased about."
Despite losing her baby weight fairly quickly, Billie insists she's not on any strict diets or gruelling exercise regimes.
She continued: "When you're a new mum, you need a lot of energy so I would never do something like deprive myself of carbs.
"If I'm cooking for me and Greg, I do try to make a nice healthy dinner but at lunch time, I have a ham sandwich. I know it's not particularly healthy and it's boring but it's my favourite."
Following little Nelly's birth, Billie and Greg are focusing on their upcoming wedding, after recently celebrating their engagement in Marbella.
Billie told a British magazine: "Anyone would have thought it was our wedding day! It was a dream. Greg made a speech and then we had a romantic dance."
Greg also revealed some of their wedding plans, admitting they're considering having a city celebration in New York.
He said: "We're looking at September next year [for a wedding date], but I think we're going to do it abroad. We've been looking at New York or the Maldives."