Credit: NATIONAL PHOTO GROUP

Call him Mr. Congeniality: it's Louis Bardo Bullock!

After months of secrecy, Sandra Bullock brought her four-month-old son out in public earlier in May: over Mother's Day weekend in New Orleans, and several days later in Austin, Texas, as exclusive new photos in the latest Us Weekly reveal.

In Austin (where she owns a home) on May 14, Bullock was "showing the baby off to just random people in stores," a fellow shopper tells Us. "Sandra was in a really happy mood."

Bullock, 45, was "such a natural with [Louis] and so easygoing and chill," local store owner Jennifer Mazuelos says. "He's such a big boy!"

After a devastating couple months -- the revelation of husband Jesse James' multiple affairs and a late-April divorce filing -- the Oscar-winner is finally settling into full-time motherhood.

"Sandra is loving it!" a pal tells Us.

Adds another: "Having Louis around is perfect therapy for what she went through with Jesse."

While Bullock never considered adopting alone prior to her shocking split, her unexpected single parenthood has been "an extraordinary lesson for her," a friend says.

To read about how Jesse James' relationship with Louis is "still evolving," whether Bullock may adopt additional kids, her support system, and Bullock's connection to James' three children, pick up the new Us Weekly, out now!