Alessandra Ambrosio was "really worried" about losing her baby weight when she got the call to model the $2.5 million Victoria's Secret Fantasy Bra.Alessandra Ambrosio was "really worried" about losing her baby weight in time for the Victoria's Secret Fashion Show.The Brazilian model got a call about modelling the label's $2.5 million Fantasy Bra at the annual event while she was breastfeeding. But the coveted opportunity brought on intense anxiety. "I just wanted to scream. But I won't lie, I was really worried. I was in total mother mode," she told People magazine. Alessandra, who is married to businessman Jamie Mazur, gave birth to their son Noah on May 7.The 31-year-old mother-of-two credits a strict diet and plenty of exercise with helping her to snap back in shape."I was playing a lot of volleyball on the beach, swimming and running after my kids," she said, adding breastfeeding also helped her along.Her regime has clearly paid off.A newly-released promo of Alessandra in the diamond bra shows her looking fit as ever. The model is currently preparing for her return to the runway for the annual extravaganza. Fellow Angels Miranda Kerr, Doutzen Kroes and Erin Heatherton are also expected to participate in the televised event, featuring performances by Rihanna and Justin Bieber. The show will be taped next month and air on US network CBS in December.