Nowadays, we say a girl becomes a naarah when she reaches age 12 and a bogeress, when she reaches age 12 1/2, at which point she is no longer called a naarah. At what age, or under what circumstances, do we stop considering her to be a bogeress and just refer to her as a woman?
Bogeress is essentially an independent, mature woman. This happens 6 months after the physical, Halachic signs of puberty, but not before 12 and 1/2 years old. This the category she remains in for the rest of her life.
If a woman's puberty is delayed to 30 days into her 20th year (or another opinion is 30 days short of 20 years old) and she shows the Halachic signs of barrenness, she then has the status of Bogeress.
If she doesn't reach puberty but also doesn't have the signs of barrenness, she is a Bogeress at age 35.