I believe, based on this reference, that she was the daughter of this Mariana Waldstein.
The dark shading beneath María Ana's over-skirt suggests her dress has a separate bodice, making it more complex than Directoire styles. Gold thread marks the boundary of the over-skirt and also her train.
Keywords: 1802, Goya, Maria Ana Silva-Waldstein, Countess, Spanish, curly hair, floral headdress, scoop décolletage, modesty piece, quarter length tight sleeves, train, waist band, Empire waistline, over-skirt