Davina Ayrton, 34, admitted being sentenced for having the images in 2014, but denies committing rape in a garage in Portsmouth in 2004.
The girl, aged 15 at the time, met Ms Ayrton, then called David, on the day of the attack, the jury was told.
Portsmouth Crown Court also heard the girl had run away from home.
Ms Ayrton, who has a son, admitted being previously sentenced at Bournemouth Crown Court in January last year.
When Ann-Marie Talbot, representing Ms Ayrton, asked her why she entered guilty pleas, she replied: "Because I was guilty of them."
Ms Ayrton admitted being in the garage in the autumn of 2004 and drinking four cans of Foster's beer but denied drinking vodka because, she said: "I was on benefits at the time and didn't have enough money".
The attack is alleged to have taken place while two other people were asleep nearby.
The teenager, who cannot be identified, said she had "only drunk a can and a half of Foster's" and clearly recollected the events.
The court heard that Ms Ayrton has learning difficulties and told a worker at the care home where she lives in Fordingbridge, Hampshire, about the incident in 2014.
But she denied confessing to the care worker that she was a paedophile, or saying: "I have always known there was something wrong with me and I need help."
Ms Talbot asked the defendant about her sexuality, and whether she had "made any physical changes or enhancements" to her body or was taking any medication.
The defendant replied "No, I have not" and said she changed her name in 2012.
Ms Ayrton denies one charge of rape between October and November 2004.
The trial continues.
A transgender woman accused of raping a girl when still living as a man, has a conviction of possessing indecent images of children, a court has heard.