The woman identified as Jasmina Milovanov alias Assma Abdullah, left her two kids with a babysitter in April this year to join ISIS.
She told her friends that she is going to Queensland to buy a new car, Australian Broadcasting Corporation reported.
Assma's friends were contacted by police to know about her whereabouts.
One of her close friend said authorities visited family and friends after it was revealed she had left the country.
"The authorities were investigating those of us closest to her. I had police come to my house wanting to speak to me," the friend said.
"None of us had any idea but she's obviously been contemplating this for a while," said her friend.
Family and friends failed to contact her when she did not return for her children.
Family members became aware of Assma's location when they got a message via Facebook that she had travelled to the Middle East.
"She never came back [but] we received a message on a Monday saying she was in Syria," a source said.
"She's not a terrorist. I don't believe she's gone over there to fight," said a friend of her.