Maxwell Drew Johnson will become a big sister in 2013.  But for now, the eight-month old can revel in being an only child -- a completely adorable one!

On Tuesday Dec. 18, Jessica Simpson's fiance Eric Johnson went shopping at the James Perse boutique in Beverly Hills with his blonde daughter (wearing a pink sweater and with a bow in her hair) in tow.

PHOTOS: Maxwell's baby album!

With another caretaker in tow, the former NFL pro, 33, browsed the wares at the upscale men's store.  "He is amazing with Max," a pal told Us Weekly recently of Johnson.

Born in May, Maxwell also gets along famously with her mama, of course. "Maxwell is a total mommy's girl," another pal says. "She just wants to be held by Jessica."

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Next year, Johnson and Fashion Star mentor Simpson, 32, will have even more to celebrate: Engaged for over two years, the pair are currently expecting their second child together, as Us Weekly revealed exclusively last month.

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And baby number two should bring the pair even closer together. "Pregnancy did wonders for their relationship," another source says. "Eric, of course, dotes on Jessica. They're both very much in love."