Missing Nida Ul-Naseer, 18, vanished after university asylum row
Missing teenager Nida Ul-Naseer was upset before her disappearance because her family's asylum-seeker status barred her from attending university.
Her sister Shamyla made an emotional appeal at a press conference for the 18-year-old from Newport to return.
Sixth-form student Nida, from Pill, whose family is challenging a failed asylum bid, disappeared 11 days ago.
Police have begun searching three sites - the Transporter Bridge, Lysaght Institute, and Pill Millennium centre.
At a press conference on Tuesday at Newport police station, Shamyla Naseer, 23, appealed for her sister to return home.
"We are all worried about you," she said.
"We all need you. We can't live without you.
"We're desperately worried about you. Please come back home. We need you at any cost."
Ms Naseer described her sister as a "very religious, very shy and quiet person and very lovely".
Nida was desperate to go to university and the family had rowed about it just before she went missing.
She vanished after taking out the bins. She was wearing no shoes and had none of her possessions - phone, money or coat - with her at the time.
Ms Naseer explained: "She wanted to go to university. It was not a dispute - she just wanted to go to university.
"Because we are asylum seekers we are not allowed to go to university.
"She was angry about that. She was very sad, she was very angry about her future."
But Ms Naseer replied "no comment" when asked how soon after the university row Nida disappeared.
The family sought asylum after coming to the UK from Pakistan five years ago. Their application was turned down a year ago and they are currently appealing.
'Angry and crying'
Her father Naseer Tahir, 54, was visibly upset during the conference.
Recalling the argument over university, he said: "We were very angry and crying. She worried about her education.
"Maybe she thought I was lazy and not able to provide the education she wanted."
He added that as "head of the family" he felt she blamed him.
He then made a direct appeal for his daughter to come home saying: "We miss you, we love you, we worry about your future."
Ms Naseer told the press conference her sister did not have a boyfriend and did not go out with any other friends apart from her sister.
She wanted to go to university to become a marketing manager or finance manager.
"I think that not being able to go to university is the reason for her leaving," she said.
South East Wales AM Mohammad Ashgar described Nida's whole family as "totally devastated and really worried" about her disappearance, adding that her mother has been unable to sleep.
He told BBC Radio Wales: "She's got three sisters and two brothers, and they're all... really worried about her."
Supt Mark Warrender, of Gwent Police, said investigators had checked her computer, her phone and her bank account and they remained "extremely anxious".
'Remains a mystery'
He told reporters "substantial" amounts of CCTV footage was being examined, friends and family had been interviewed and officers had distributed leaflets around her home a week after she went missing.
"Despite all of this, Nida's disappearance remains a mystery," he said.
On Tuesday afternoon, officers searched areas around the Transporter Bridge, the Lysaght Institute, which is a yard on Corporation Road, and Pill's Millennium Centre.
When she was last seen, Nida was wearing jeans and a black top.
She is of Asian-Pakistani appearance and has long dark hair, is slim and 5ft 3in (1.6m) tall.
Gwent Police have asked anyone with information to contact 101.