Back in 2003 my then girlfriend (and now wife
) liked the idea of cycling but hadn't done much for years, she's 5ft and not particularly long legged, she ended up with a new Trek albeit a 2002 model, 14", and WSD (women specific design) although it was close with a slightly better Trek, not WSD with disks. Some of the geometries really didn't fit and things like reach to brake levers etc made a big difference.
We got it at Evans in The Cut at Waterloo who were brilliant in terms of measuring her, digging out various bikes for trying and, as they didn't have many of the really small built, building lots more. We also tried a couple of other shops for greater variety. She ended up with the one that she liked and felt best on, and ended up using it quite a lot including to cycle across central London to go to work before we moved out, ie not just a fad. I think going to somewhere with a wide selection will give a chance to try, there is a huge variation we found in even the very small bikes.