The Catholic teenager was in the bar with Protestant friends on Saturday 4 May when others made comments about her religion.
Minutes later, the young victim was being punched and kicked.
Her mum explained: "As my daughter was being attacked, her friend tried to help. She was subsequently attacked then for trying to help my daughter."
As the three women left the bar they were assaulted again, but made it to their nearby flat - followed by an armed gang. Police called to the scene brought the women to safety, but the mother still believes her daughter is "very lucky to be alive".
I'm lucky that I'm able to sit here and to tell the story that my daughter's alive - but, at the same token too, she very easily could be dead.
She said: "I'm lucky my daughter's not lying under my window in a brown box, and that also applies to the other girl that was in the bar. Because, as far as they're concerned, she brought [my daughter] into that area."
On hearing of the attack, the woman said she "panicked ... imagined the worst" and described the following days as a "living nightmare".
She said: "If they had got into that flat ... Why would you go to somebody's flat with weapons?
"If those police hadn't have come in time, my daughter most definitely would be dead."
The teenage victim has woken up crying, and has been hurt physically and mentally by the attack.
It was a very disturbing attack and I think, for a lot of people, reminiscent of the brutal attacks of the Troubles that I think most of us thought we were well past now.
Claire Hanna, SDLP
SDLP councillor Claire Hanna has called for arrests to be made.
She added: "This sort of attack is a very angry manifestation of sectarianism and terroritoriality that we need to move on from. The young women involved in this are from a post-Troubles generation - by all accounts, people who were actively integrating and, like most people, just wanting to get on with their neighbours.
"We can't have that generation growing up knowing the sectarian geography of the city."
In a statement, the First Belfast Glasgow Rangers Supporters Club claimed that this was a domestic-related altercation.
The club states that at no time were iron bars used or sectarian abuse, adding that the club does not tolerate sectarianism or violence in any shape or form.
Loyalist sources have denied that the attack was carried out by members of the UVF.
Police confirmed one line of inquiry is that the assault was a sectarian hate crime.