Size 15 women's casual in Australia
Online fashion giant ASOS has a huge range of shoes in size 11 AU. Plus many of their own brand shoes are available in size 12 or 13, with a few styles now going up to 14 and 15 AU too - all at affordable prices. While I found their size 11 AU true to size, I've had some feedback suggesting larger sizes run small, so you may need to size up. Free shipping with AU$80 spend & free returns on all orders. 10% student discount.
Allbirds make sustainable comfy casual & running shoes with natural materials. The women's range only goes up to 11 AU, but several styles are completely unisex & available via the men's collection. Order a size 1.5 smaller in men's than your usual women's size. Allbirds are a bit pricey but they have a 30 day trial which is highly unusual. So you can still get your money back after wearing them if they don't work out. Free shipping with $60 spend and free returns too.
Australian retail & online store with a wide selection of brands and styles available, including their own Jacob+Therese label. All sizes catered for up to size 16 AU. You can also visit their store in Moranbah, Queensland. Worldwide shipping available. Free Australian shipping with $150 spend & flat shipping rates for New Zealand and the rest of the world.