Maria Anna Josepha, Countess von Khevenhüller-Metsch with husband and son, an 1871 copy after a Heinrich Füger painting of 1792
She married on September 28, 1789 at Wien, Austria, when she was 18 years old. She was 19 years old when her son was born. On this painting she would be 21 years old and her son two years old. She was also known as Josepha von Khevenhuller-Metsch.
Notice this painting by Goya, depicting a boy in a very similar attire as the boy on this painting, about a decade earlier, on my other post here.