It's kind of strange. I have two sisters who are named
Patricia and
Pamela. When they were children, they went by
Patty and Pammy. As they got older, Pammy became just
Pam but
Patty stayed
Patty. Having her named shortened to
Pam wasn't something that
Pam insisted upon, it was just something that naturally happened.
Patty seems fine for an adult woman, but Pammy doesn't. But why, exactly? I can't really say. It just IS that way.
Anyway, my older sister's best friend as a teenager was named
Joni. Her name was actually
Joan, but that's how she spelled Joanie. She always continued to be called that and never shortened it to
Joan. Maybe that's why I think Joanie is perfectly suitable for an adult.