Wiktionary
preteenage
a. Younger than teenage; often specifically of an age shortly before the teens, such as 10-12.
Usage examples of "preteenage".
On the few occasions since her preteenage years when she had been awake and alone at dawn without some responsibility to fulfill as the reason, she had a lonely but somehow uplifted feeling—a paradoxical sense of newness and continuity.
Against one wall sat a gigantic desk and at the desk sat a gigantic woman who could easily fulfill every preteenage boy's nightmare of the ultimate authority figure: a combination of the wicked witch of Oz and Grendel, with traces of Bigfoot and the Marquis de Sade thrown in to improve her looks.