I don't know how any woman who said that they are size 120 can put on a medium and be comfortable!  Im one 116pds and I got the the XL. It was tight but it was still comfortable the only problem I have is the straps dug into my shoulders.  Love that you have to pinch a few buttons then zip it up- that was when wearing a tight dress the pincher parts won't show! Greatest part is the crotch area just has a hole instead of pinchers !  So you can actually maybe put underwear over it and when you need the bathroom you could just take the underwear off and not bother with taking it off.