There are a lot of ever-changing details to US immigration law and I find that a lot of well meaning people on the internet will often give bad advice. For instance, you mention your partner is from Australia. I happen to know that there are some immigration rules that are different for Australians than for citizens of any other country, due to a bilateral trade treaty. In this case, they happen to be especially favorable. But even somebody who is quite familiar with the process and has gone through it themselves, if they are not involved with it on a daily basis in a professional capacity, could easily miss such a detail. Also, while you probably just meant to say you don’t plan to have an elaborate wedding, you need to be careful writing things on the open internet like “not the big marriage”. You don’t want a literal-minded immigration official to google your name and find any evidence that your marriage could possibly be intended just for immigration.