Well, now that I'm in Bangkok, I have an update regarding my 90 visa.
First of all, the many commentors pointing out that it was actually only a 60 visa, and I would find out once immigration stamped my passport, well they were correct.
Why did I think I had. 90 day visa? Well because I spoke with the Thai embasssy in Austrlia and was advised to apply for an e-visa and selcted 90 days as duration of stay and upload inbound and outbound flight details. Which I did.
Worst part is that it cost me AUD$300 to apply for a visa that I did not need because Australian citizens get 60 days visa exempt on arrival.
Thanks to all that commented.
TLDR : Answer Summary
The original poster learns that they were issued a 60-day visa instead of a 90-day visa after consulting the Thai embassy, despite initially believing they applied for a longer stay. They express regret over the AUD$300 fee for a visa they didn't need, as Australian citizens can enter Thailand visa-exempt for 60 days. The discussion among commenters highlights the options for extending stays, including applying for a 30-day extension and clarifying differences between single-entry and multi-entry tourist visas.