Raehamilton, sounds like you have someone who knows her stuff and is more than willing to help you with any problems you may have, you are lucky indeed. We here at the forum will help you all we can but we are amateurs at most, some are more knowledgeable, and a few are experts at it. Most of the time people who sell the birds think that after the sale you are on your own and don't bother me with anything.
I have heard that the shape of the head and the shape of the eye can tell the sex but it is not accurate, but if she has seen many over the years she may be able to tell, she has a keen eye for detail maybe. As far as age I know a baby has dark eyes that lighten up as they get older. She is good, really good and you are lucky to have found her.