Size 11 Extra wide width women's casual in Canada
You can get great deals on large size shoes at Amazon with a bit of patience. Their own Amazon Essentials range up to size 15 US is well worth a look with fashionable styles at great prices. The women's shoes department goes right up to 16 US, although many of the largest sizes will either be Chinese brands or unisex.
Famous British shoe brand with selected shoes, boots and sandals going up to size 12 US. Free shipping & returns for Canada. Many styles also come in wide fit, with a few narrow and extra wide styles available too. Clarks are the brand I've been able to rely on most over the years for comfortable everyday shoes particularly their cloudsteppers and unstructured ranges. Clarks also have Canadian stores and are widely stocked across Canada, although these may not have larger sizes in stock.
Known as 'The Bay', this famous department store has over 80 branches across Canada. Their online store usually has around 1000 size 11 shoes, about 100 size 12s and a smaller range of size 13 shoes in stock with free shipping and returns. Brands include Clarks, Sam Edelman, Cloudwalkers, Aravon and Cole Haan.
Specialist large size shoe store in Quebec also selling online to Canada ($10 flat rate shipping) with a wide range of women's shoes in sizes 10 to 15 US, with selected fantasy styles up to size 17 US. Large selection of brands and styles. They even do rain boots, slippers and socks. They are happy to advise on the right size for each style if you send them your foot measurements before ordering or during checkout. You can also visit their shop in Rue St-Hubert, Montreal. Website is in french.
Canadian family owned store shipping to US & Canada with select shoes, walking sandals & boots available up to size 13 us including some narrow, wide & extra wide fit. Mainly comfort and traditional styles. Several stores across Ontario. Note that you cannot return online orders to stores & must pay return shipping costs.