Credit: Scott Gries/ MTV/ PictureGroup

Teen Mom star Amber Portwood is slamming two new tabloid claims that she's expecting her second child.

"The rumors are absolutely false. I'm not pregnant," Portwood, 20, tells in a statement.

"I'm working hard to be the best mom to my daughter," she adds of Leah, her 2-year-old with ex-fiance Gary Shirley. "I have no plans to have more kids anytime soon."

After several weeks of living apart, little Leah was reunited with her mom Dec. 6 at Portwood's new home in Anderson, Ind. (Portwood's former home had been besieged with photographers and curious neighbors.)

Portwood "is so excited to have Leah back!" a source told Us.