I just posted a link to E Online's collection of posts regarding Dawn: Marsters, Gellar, Caulfield, Hannigan, Lively, Crawford, Cattrall, O'Donnell... there's more out there. She had a lengthy career prior to Buffy. And Buffy was only 3 years of her life, actually less than that - they film about half a year. So about six months a year? She starred with Kim Cattrall in Ice Princess, and O'Donnell in Harriet the Spy. This was long before she got the role of Dawn on Buffy.

She lived a good life. And wisely stayed off a lot of the internet (Buffy fandom was obnoxious about Dawn. When they fans hate a character - they kind of become toxic about it on the internet.)