Marie Claire on MSN: Royal biographer vows to do justice to Queen Elizabeth after King Charles commissions biography
Royal biographer vows to do justice to Queen Elizabeth after King Charles commissions biography
International Business Times UK on MSN: Who is Anna Keay? Here's why King Charles chose a specialist for Queen Elizabeth's biography
Queen Elizabeth II's official biographer, Anna Keay, is the first woman in a long line of esteemed British monarch historians. King Charles III has appointed historian Anna Keay as the official ...
Who is Anna Keay? Here's why King Charles chose a specialist for Queen Elizabeth's biography
"Adult children" comes from "adult children of alcoholics", but now has broader reference to adults who were abused emotionally, physically or sexually in childhood.
Merriam-Webster has an entry for half-orphan, meaning someone with only one living parent. They say specifically a child, which would match the usual usage of "orphan" (as mentioned in the question), but it might be used of an adult sometimes, either jocularly or by extension. This doesn't distinguish which parent is dead, but could be combined with a further explanation if it matters.
The best way to do it, I think, would be to forgo the hyphens completely and go with: I am a psychologist who works with children and adults. Anything else is awkward, ambiguous, or both. If it's necessary to emphasize that this individual works with children and adults (i.e., this isn't just introductory information), you could add in a 'both': I am a psychologist who works with both children ...