I'm a bit confused.
Do we know for sure what she does for work? I may have missed it, but I only saw a mention of previously being an event planner. Is she still in that business? What did she have on that weekend in Dalby? The info seem very vague.
The timeline fits well with the sightings: from Dalby 8am she drives 2h45min roughly to Surat (she was seen at 11.10am), maybe stops for food/toilet/fuel etc, then 45-50 mins to Yuleba (her phone pinged there at 12.13am).
The question is why was she going towards Yuleba instead of straight to Roma from Surat?
The fact that it was the last ping and went dark after that and the fact that the car has not been found, makes me worry about the usual "person+car in body of water".
From what I can see on Google Maps there's a lot of state forest in the area, and a few bodies of water, one of which (
The Maryanne dam) in Yuleba south looks very close to the road. Not sure if the dam is full and how deep it is at this time of the year though.