At an earlier court hearing, she claimed that she had been forbidden to have children, as well as being made to take lithium, a powerful mood stabiliser drug with serious side effects, against her will.
Among the allegations she levelled on Wednesday were claims that her hair vitamins and coffee had been taken from her.
“Ma’am, that’s not abuse, that’s just f—ing cruelty,” a tearful Spears told Judge Brenda Penny. “Excuse my language but it’s the truth.”
The singer, who took a short break to compose herself, demanded her father be removed from the conservatorship and be charged with “conservatorship abuse”.
In a victory for the singer, Judge Penny permitted her to hire a lawyer of her choice during the proceedings.
Spears has chosen Mathew Rosengart, a high-powered Hollywood lawyer and former federal prosecutor, to represent her.
He told the court his law firm was more than capable of handling a complex case.
His arrival is expected to signal a more aggressive approach to ending the conservatorship.
Mr Rosengart’s first job is likely to be filing a formal document asking for the conservatorship to be terminated.
Spears’ court-appointed lawyer, Samuel Igham, stepped down after the singer gave emotional testimony in June calling the conservatorship abusive, stupid and embarrassing. An estate-management company that was supposed to oversee her finances also withdrew from its post.
In response to his daughter’s claims, lawyers for Jamie Spears have previously said: “He is sorry to see his daughter suffering and in so much pain. Mr Spears loves his daughter and misses her very much.”
Spears reiterated on Wednesday that she wanted the conservatorship to be terminated without the need for a medical assessment, but indicated her top priority was ousting her father from his role while allowing co-conservator Jodi Montgomery to remain.
“My dad needs to be removed today and I will be happy with Jodi helping me,” she told the court.
The hearing took place inside a packed court in downtown Los Angeles, with around 60 masked journalists.
Outside the courthouse, dozens of fans held a rally, chanting “Free Britney” and calling for the conservatorship to end. Among them was the Republican congressman Matt Gaetz, who called for changes to legal arrangements like the one governing Spears’ finances and personal life.
“Every time there is a hearing in this case that does not result in freedom for Britney Spears and dissolution of her guardianship, it is a black eye on the American justice system,” Mr Gaetz said.
A smaller rally took place near the Lincoln Memorial in Washington, DC.