Where can I find shoes for women with large feet?

Try one of the larger shopping centers with several boutiques.  My wife found EU41 size shoes in various styles at Central Festival in Pattaya -- Bangkok stores on Sukhumvit are sure to have an even wider selection, being a bigger city and with a larger expat population.  She bought sneakers, open toe walking, and high heel shoes here without issues.

There are a couple of shopping malls along Sukhumvit/Bangkok -- Terminal 21, the one where the Apple Store is, etc. where you can spend some time exploring.

Good luck!

Thanks very much.