My wife is petite (4'11") and always struggled to find clothes that fit her. She dresses conservatively because we're Muslim but she doesn't really like wearing the long gowns that many Muslim women wear, so she wears jeans and long sleeved shirts. Anuway, she always struggled to find clothes that fit her well because she's small. Her uncle had to tailor a lot of her clothes growing up. A while back she found a fashi…
I went to Vietnam and noticed the sizing difference for myself: suddenly I was oversized. I've also seen the opposite in other countries where sizes are much bigger and I'm on extra small sizings.
Vietnam is great for getting tailored clothing too - if you can avoid the worst of the tourist tailors.
Worth a try, if you can find a country that has a style she likes...