S for Driducks would still be gigantic for women. Driducks are huge even for men!
As for MontBell, remember it is a Japanese company, sized for Japanese. If you look inside the garment at the label you will see the size equivalents for different areas of the world. "M" in Japan is "S" in America and Europe. 26-28 is the average waist size of women in Japan. Yes, women are very slim here. And just imagine, my Japanese partner has Japanese size "S" (XS in America and Europe) and think how small the waist is on those!
Be careful with leg length sizes. Japanese pants legs are shorter than those of Americans and Europeans. Also bust sizes can be considerably smaller in Japanese garments.