The name of the woman cannot be published because she was underage at the time of the killing.
The woman argued on appeal that the sentencing judge failed to consider expert evidence that indicated incarceration was not necessary and might even be harmful to her.
However, the B.C. Court of Appeal ruled Tuesday that the sentence, which also includes nine months of community service, complied with the Youth Criminal Justice Act.
The court ruled the expert evidence dealt with an adult facility as opposed to a youth one, and the sentencing judge crafted the sentence so the young woman would be placed in an appropriate facility.
Ashlee Hyatt of West Kelowna was stabbed in the neck outside a house in June 2010 during a fight over a boy.
The young offender who killed Hyatt was originally charged with first-degree murder, but that was later reduced to second-degree murder before jurors settled on manslaughter.