Couple of positives is that your gf not 20 also one year relationship.
It is possible for Loa to obtain visa for Oz while in Thailand.
For sure you will need an agent.
Thinking best for you to do personal visits to the many good agents in Pattaya.
Also you being in 30,s you need to demonstrate ability to support her stay.
Not only that (in my case 10yr back) you need to wack some money in a her Thai bank account, which I think you posted that she does not have.
If I was looking at application would be a reject.
"No compelling reason to Return" to Thailand.