, meet Thomas the Tank Engine.
The actress recently took her 2-year-old son Louis
to a meet-and-greet with a full-size version of the famous train – one of many Mommy-and-me outings for the inseparable duo.
"Being a mom is her total focus now," a Bullock source tells PEOPLE in this week's cover story. Along with her work, "Louis has become her whole life."
Currently renovating a $16 million Beverly Hills mansion, the Oscar winner
, 47, regularly shuttles between work at her Fortis Films production office and her son's preschool.
"She is raising Louis as a single mom, and she never thought it would be this way," says another Bullock source. "She's still trying to figure out [her new life]."
For more on Sandra and Louis, pick up this week's PEOPLE, on newsstands everywhere Friday