Shauna Rooke, from Bridgend, was left ‘black and blue’ after the attack, in which three girls kicked her repeatedly.
After the beating, she lay helpless on a dual carriageway while cars went speeding past and said she believed she would die.
Shauna has criticised police for failing to act sooner, saying they have ‘really let her down’.
Chief Inspector Stephen Jones has personally apologised to Shauna and her family, saying he is ‘bitterly disappointed’ in the progress made in the case.
“We have met the victim’s family and reassured them of our determination to bring the assailants to justice,” he added.
“I can only apologise to the victim and her family for the lack of progress made to date and we will continue to support them throughout the rest of the investigation and beyond.”
The Bridgend high school pupil was targeted by the three girls, who she believes to be older than her, after standing up for herself in a dispute with a girl from another school.
Shauna still suffers nightmares about the attack, adding: “I have been feeling depressed, I can’t sleep properly and I don’t really go out much any more.”
<b>See more:</b> <a href=”http://www.itv.com/wales/”>Interview with Shauna Rooke</a>