You're right, women's non-unisex DM styles like these and their ballet flats and high heels seem to top out at UK 9=EU 43.5, which is apparently equivalent to US W 11.25. Most of their dress flats, though, are unisex with a bulkier sole like these, and go up to UK 13 which is ... actually I'm not sure because international sizing conversion charts are rubbish, but US W 12 should be a UK W ... 9.5. Probably!