As far as little Leah Shirley is concerned, her mom is in Hollywood shooting a film. That's a far cry from the reality of Amber Portwood's situation. The former Teen Mom star is actually serving out a 5-year jail sentence for violating her probation. She was originally charged with felony drug possession and could have avoided the lengthy prison stay by completing a drug program and taking routine drug tests. However, Portwood's drug demons were way too much for her to handle on the outside. She opted to serve out her time rather than be at the system's mercy. Of course, daughter Leah is no more the wiser. She thinks her troubled mom is actually working on her career in Tinseltown. A source tells Radaronline.com, "Amber and Gary are going with the idea that she is away shooting a film in California. This is their cover; they don’t want to tell Leah that she’s actually in prison -- because they’re not sure she would understand and don’t want her thinking worse of her mom." But even the best-laid plans go awry...and these likely will. As it so happens, everybody and their brother is well aware that the 22-year-old reality star is locked up. The insider adds, "But the problem is, everyone at Leah’s daycare knows that Amber is her mom and that she’s in prison, there’s no hiding that fact. So, it’s only a matter a time before Leah overhears it, and that has got Amber and Gary in a panic that she will find out what’s going on before they tell her." Meanwhile, Portwood's latest project is herself. According to Radaronline.com, she is keeping busy with the prison choir, parenting classes and daily workouts. And she's doing it all for little Leah. Says the source, "Amber is well aware she hasn’t exactly been the model mom for Leah, and she will do anything to make it right. It took time, but she’s now taking a hard, long look at herself in the mirror and realizing she needs to make it up to her daughter."