"She had the awareness she wasn't feeling great," Ms Pucci Love said.
"We were working very hard to get her that extra help, but sometimes those things don't come quick enough."
Ms Pucci Love said her sister was a unionist and someone who always fought for what she thought was right.
"She had empathy for the community around her and an interest in social justice," she said.
Ms Flack's communication had not been out of the ordinary in the days leading up to her disappearance, Ms Pucci Love said, causing additional worry for her family.
Bridget is a part time DJ who cares about social justice and gender issues.(Nine)