Cottrell was raised in Michigan, moving to San Francisco in 1968. She learned photography in her twenties and in her thirties, and went to school at San Francisco State University, earning a Bachelor of Arts in film studies. She funded her early artistic work by serving as a waiter on cruise ships, earning a certificate as a merchant seaman.
She began exhibiting her photography in the mid-1970s in San Francisco, becoming well known for her photography of women.
She collaborated with other lesbian photographers, including Tee Corinne. In the 1976 documentary film We Are Ourselves, Cottrell and Tee Corinne describe their relationship to filmmaker Ann Hershey.
Her work in the book "I Am My Lover" focused on images of women and on lesbian sexual Cottrell"s first film, Sweet Dreams (1979) included Pat Califia and was produced by the National Sex Forum.
Sweet Dreams is described by documentary film critics as part of a tradition of the "feminist autobiographic art of masturbation demonstration".
Through the 1980s and 1990s, Cottrell worked as contributing photographer for On Our Backs, a lesbian sex magazine edited by Susie Bright. Her work became influential in representations of lesbian sex and feminist lesbian portraiture. Along with Corinne and later, Susie Bright and other lovers and artistic collaborators, Cottrell strategically positioned sexually explicit photography as part of lesbian culture and as populist sex education.
Her lesbian s/m images in particular, in works such as the SAMOIS book Coming to Power, were considered controversially pornographic by feminist critics.
She worked for Fatale Media as a consultant, a film company known for getting the first lesbian porn film into the Frameline Film Festival in 1985.