Seems like you are pretty much at the mercy of that parole board then. Are there any rules they base their judgement on, or is it just their personal “gut feeling”? I once saw a documentary about an (in-)famous prison in Louisiana (“The Farm”) where the parole board knew what they would say (from internal discussions before hearing the inmate) before he would even report to them. And when he would get a “no”, it meant another five years of waiting…
In Europe / Germany you can get a parole (probation) after serving 2/3 of your sentence, if a court decides that you are no threat to society anymore and unlike to commit further crimes, unless the court decided on “severe guilt” for special crimes (like serial killers / rapers), where a parole / probation can be excluded.
EDIT: so, in Germany with that sentence she would most likely leave prison at the age of 29, being able to start a new life, if it’s unlikely that she would commit the same or a similar crime again (of course not possible if a psychiatrist diagnoses her to be a threat to society). I know that she took two lives, but if she rots in prison, it will not make them alive again either.