Suspicion arose after pictures emerged of pal Poppy Delevingne touching her stomach during a night out on Thursday.
A spokesperson for the lingerie model later confirmed the news to HELLO! Online.
In June of last year, Florence married millionaire Henry St George in a romantic ceremony in the south of France.
The beautiful bride, who was Harry's first girlfriend after he split from Chelsy Davy in 2011, looked exquisite in a lace gown, veil and with her hair tied loosely back.
Guests at the wedding included model Poppy, who posted a photograph of the newlyweds on her Instagram account and also shared a snap of herself in a glamorous Gucci gown.
Model Florence, who is known to her friends as Flee, first dated Henry in 2008. The couple split in 2011, and she was linked to Prince Harry that summer.
The socialite was not comfortable with the attention that came from dating a royal, and quickly went back to Henry.
"Henry has been around a long time," a source was quoted as saying. "Harry was more of an affair. Flee hated all the press attention she got when she was dating Harry. She really liked him but she was embarrassed by being splashed all over the papers." Flee had another high-profile romance when she dated Formula One racing driver Jenson Button.
She soon realised that her split from Henry was a "blip". They reunited and Henry, 28, popped the question when they were on holiday in New York last Christmas.
Flee is a descendent of the Earl of Cardigan , who led the Charge of the Light Brigade. She is a cousin of The Voice singer Bo Bruce and has modelled for high-profile campaigns including Aspinal of London.
Flee’s new husband Henry is the son of the late financier and racehorse magnate Edward St George, who was a close friend of the Queen. Henry is vice president of The Grand Bahama Port Authority, so he and his new wife will divide their time between London and the Bahamas.