Two years after her shocking split from her husband, Sandra Bullock revels in private time with her adorable two-year-old son Louis Bardo Bullock. This week's issue of PEOPLE takes a look at how the 47-year-old Oscar-winning actress's world revolves around the love of her life as the whole world has watched Louis grow from a cherubic baby to a fun-loving, likes-to-paint-and-get-his-hands-dirty little boy. "Being a mom is her total focus now," a Bullock source tells PEOPLE. Along with her work, "Louis has become her whole life."

For Bullock, going it alone as a mom wasn't the dream she signed up for, but it is one she's embraced. "Sandy seems very happy, but it's hard," says another Bullock source. "She's raising Louis as a single mom, and she never thought it would be this way. She's still trying to figure out [her new life]." She's thrown herself into giving Louis the most regular-kid life he can have given her celebrity. From shuttling him to preschool to setting up playdates and special outings, she's "very hands-on," says a source. "She is giving him the best, most normal life she can."

Having wrapped the outer-space drama Gravity with George Clooney (due out in November), she's been settling into life in L.A., where Louis goes to preschool. Bullock has been renovating a $16 million, 8,100-sq.-ft. Beverly Hills mansion that she bought last year to serve as a permanent nest. "Sandra is putting a lot of money into the house to make it comfortable and safe for her son," says a source. Working at her Fortis Films production office, she squeezes in meetings and workouts with a nearby private trainer before Louis gets out of school. "Louis is a really outgoing, funny little kid," says a Bullock source.

Over the past year Bullock has occasionally hung out with model-mogul Heidi Klum, 38, herself a newly single mom after splitting from husband Seal earlier this year. When the two were introduced by a mutual pal a year ago, "Sandra was on her own as a mom and asking Heidi the tips and tricks [of motherhood]," says a friend of Klum's. "Now it's more advice from Sandra to Heidi, talking about being back in the world and what it's really like." Klum's kids – Leni, 8; Henry, 6; Johan, 5; and Lou, 2 – have enjoyed playdates with Louis, while their moms have gone out to dinner with other friends. The two business-savvy women, who share German roots, "both like to laugh," says Klum's friend. "They both have experienced ups and downs that the world has followed. They see the funny side of life."

As for romance, Bullock would like to find someone she could get serious about, says a source. But she's doing just fine on her own: "Louis has grounded Sandy and helped her focus on other things." Bullock's fondness for her close male friends – best buddy Jonathon Komack Martin is producing partners with another old pal, Ryan Reynolds – sometimes sparks romance rumors, but the relationships are strictly platonic. As much as the world may want to see America's sweetheart happy and in love, it's not something that Bullock is going to rush into, says a source. "She is going to be very careful about who she allows in her life because of Louis," says the source. "He is her priority. He is her world."

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