This might not be good advice because I've read different things about them. Being not so good, too much torque, but a Buell Blast is a small bike that you MIGHT be able to fit on. I think the seat heat can be as low as 27.5". I'm not sure if it would be low enough or you.
I would think an older Honda Rebel would probably fit, but like some say, a completely opposite end of the spectrum as a sport bike.
I wonder if any of the small bikes would work for you to begin with. Like the Honda Grom or the Kawasaki Z125. And then there is one called the SSR Razkull. I'm sort of interested in the Razkull cuz of price and my Daughter wants to learn how to ride too. She's a bit taller than you but not much.