dhoppy, the only way to make a reasonable guess as to the age of your picture is if you know the approximate age the person was when the photograph of the person was taken that the drawing was made from, that’s assuming that is how it was made.
I say that because the wife has similar sized pictures of her relatives, one of which she also has a copy of the photograph it was made from. She was told that another relative had sent the photographs to an artist somewhere who “drew/painted” the pictures from the photos. She also has a photo of another picture of an Aunt that was made using pastels (colored). See the following 3 photos.
The 1st one is a photo of an actual photograph of her Aunt (1881-1917) and the 2nd one is the charcoal drawing of her. The 3rd one is a photo of the pastel drawing of another Aunt (1875-1904) .