Drawing from Memory (Rescued Sketch)

I have been cleaning my home studio, which leads to looking in old sketchbooks.  So I came across a pen-and-ink drawing of my mother.  I am pretty sure I was working from memory; the sketch didn't "match" any of the photos I have, and it didn't look like it was drawn from observation.  It looked like I had stopped working on it, probably because there were several mistakes. The main problem was that the features were not symmetrical.  So this afternoon I got out a fine point ink pen and began to draw into the sketch.  I added to the drawing to made the eyes, hair, and hairline more symmetrical. As I worked, I realized that the tip of her nose was wrong.  It was shaped like my nose, not hers!  At that point, I grabbed a picture of her, one of her wedding photos, and then made revisions to the nose. I also modified the shape of her lips and slightly changed the shape of the jaw.  Then I drew into the hair and neck, to balance light and dark.  People who knew my mom can recognize her, so I think I have the likeness. I can still see lots of mistakes, but I am happier with the sketch now.