Although I am comfortable with being addressed as Lady, as it is standard in the SCA, I would rather be referred to as Dona.
When Dom Afonso V of Portugal signed royal decrees inducting women in the tailor’s guild in 1442, Dona was the form of address employed in those documents .
I am currently working on documenting the use of Dona as an alternate title for Portuguese personas, as I have collected several documents with examples of its use during period. Although Doña and Señora are both accepted for SCA Spanish personas, currently the only documented title for Portugal is Senhora.
My preference for Dona comes from my knowledge of nuances of the Portuguese language. While both are respectful forms of address, we can trace a parallel between the connotations of Senhora and Dona to Mrs. and Ms. in English, respectively. The term Senhora comes attached to suppositions of age and marital status, while Dona is a blanket form of respectful address and was originally employed as the title of choice for Portuguese noble women.
Hence, when the use of titles becomes necessary, please refer to me as Dona Aurelia Alfaiata d’Alcaçova.