On the contrary, I stated that both may have been in their late teens. Which isn't specifically contradicted by your source either.
That said, my usual go to source contradicts this, and pegs her as about four years younger than Bruce and about 13 years older than Dick pre-Flashpoint (however, this timeline is not always authoritive, as they list Barbara as 16 when she enters college (true) and becomes Batgirl (incorrect based on the stated reference, which pegs her debut as after graduation (so at least 20), which would fit with the reference you provided above.)