It's certainly the most grown-up she's ever been and she'd been a quasi-adult for a long time. When she and Kon were hot and heavy I'd think she'd be about 17/18 and he was dead for about a decade in real time. When Bendis brought back Young Justice there was speculation here that her added layers were to hide a pregnancy, but it turned out the big reveal was she had regressed chronologically as well as in characterization.