"I just keep thinking she's going to come back," Patricia Spence, 56, told jurors at the High Court in Glasgow.
She said Lynda Spence was a "loving, caring girl" but was "very tense" the last time her mother saw her.
The court heard the adviser, 27, went to the home Mrs Spence shared with husband Jim in Castlebank Gardens, Anniesland, to give her mother flowers for her birthday on April 13, 2011.
Lynda left soon after, telling her parents she would be back in half an hour, but it was the last time they saw her.
She was reported missing the following month.
Colin Coats, 42, David Parker, 38, Philip Wade, 42, and Paul Smith, 47, all deny abducting, torturing and murdering Ms Spence in April 2011.
Solicitor general Lesley Thomson asked Mrs Spence to describe her daughter and their relationship.
"She was very happy, very positive," she said. "I never had any problems with her. She was a very loving, caring girl.
"We were very close. She was like my friend, my best friend. She took me out every Saturday.
"I heard from her every day. I was very over-protective, a bit of a nutcase mother. As long as I knew and got a phone call or a text message to say she was in. I used to drive her mad because she was like, 'what age am I?'."
Mrs Spence wept as she added: "But she was my life. I've only got one lassie. I just keep thinking she's going to come back."
Mrs Spence said she and her daughter would often go to Largs at the weekend, or out on shopping trips. But towards the end of 2010 her daughter became "distant" and often said she was too busy to meet up, Mrs Spence told the court.
"I can't explain it, she kind of distanced herself. She would have an excuse, saying 'I'm doing something'. She would still phone me but I saw her less."
Mrs Spence broke down again as she was asked to review text messages she exchanged with her daughter on April 14 and April 15, 2011, in which she claimed she had travelled to London.
As she started to cry, Mrs Spence said: "I'm sorry. It's just reading these texts."
Speaking about the last time she saw Ms Spence, Mrs Spence said her daughter was with a friend called Amelia.
"It was about 6pm on my birthday," she said. "She had brought flowers.
"I was cuddling and kissing her and saying where are we going (for my birthday). But she said she had to go. She was tense. She never said anything was wrong but she was just dead tense."
Ms Thomson asked: "Were you worried on April 13?"
Mrs Spence replied: "No. She said 'I'll be back in half an hour'. But she didn't come back."
The trial continues.