@aplfrvr hi Apl, your sister can vouch for you by sending a letter to dIBP as requirement stating that she is inviting you to visit AU, also that she will be shouldering all your expenses, airfare, lodging, cost of living during the trip.
But of course, the unemployed status of young adults is a bit of a grey area for the case officers and even if you show them a huge amount in your bank statement, they may or may not give you a visa. They need valid proof that you will be returning back to the Philippines, I'm not too sure if the thesis thing is enough reason for them but you can always try.