"She spent most days at home writing," says a friend of the late singer

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When Amy Winehouse passed away on July 23, many jumped to the conclusion that she’d overdosed after a drug binge.

But what she was really doing, say sources, was surprisingly low-key: She laid low at her London home, spent time with her mother, and had a routine doctor s visit.

In fact, while the toxicology results may not be available for weeks, those who knew her say she was much more than a party girl.

“She spent most days at home writing,” says one friend.

Beneath the disheveled beehive and heavy eyeliner was a slyly hilarious potty-mouth who loved to cook. “Amy was a sparkly character,” says Sarah Hurley, landlady of the Good Mixer, one of Winehouse s favorite pubs.

For more on Winehouse and her final days, pick up this week’s issue of PEOPLE, on newsstands Friday