While she did face significant challenges in her life - including being a single mother, societal expectations for women, and the constant pressure to live up to her famous husband's legacy - there is no record of her stating that an occupation hindered her writing.
Instead, she frequently expressed her desire to write and actively pursued her literary career throughout her life. She was a prolific writer, producing novels, short stories, essays, biographies, and travelogues.
Perhaps the misconception stems from the fact that she was often seen as Percy Shelley's wife and not as an independent author.