Gradfashionista, I feel your pain. Sorry you had such a frustrating experience.
The number on the tag of a woman's garment has as much to do with anything rational as a bag of flour has to do with the rings around Saturn. It is absolutely insane and it sometimes makes me want to go on a bleep-fest, but I don't want to get thrown out of a store or arrested LOL.
I've had the following sized pants in rotation at the same time before: an xs gap sweatpants, a large 5Preview legging, size 6 pants from cache, size 28 Helmut by Helmut Lang jeans, size 29 Joe's Jeans, size 10 GoSilk pants, size 8 H&M skinny jeans, size 30 Paige denim pants, size 2 NY&Co jeans, size 4 NY&Co trousers, and Italian size 46 Patrizia Pepe pants.
And tops? I'm anything from: size small Helmut Lang top, size large Helmut Lang top, size 14 Rick Owens sweater, size Medium AG knit top, size 8 (Italian 42) Just Cavalli top, and a size 14 Calvin Klein overcoat.
For the record, I'm somewhere in the 8-10 American size range. It makes no sense that I am wearing everything from xs to XL, because I am neither xs nor XL.
It is nonsensical. I have quit looking at sizes on tags and started actually looking at the garment to see if it looks like it will fit; that's how I pick things to take to a dressing room. I have mostly limited my internet shopping to yoox because they list Italian sizes on garments that are made to them (and if yoox says something runs small or large in letter or American number sizes, it really does); and etsy, because I can converse with the actual designer/maker and make sure I'm ordering the correct size. Anything else on the internet is a total crap shoot.
I have sat, and thought, and smoked on this matter and I have concluded that the problem is not my body and it is not your body and it is not any other woman's body. The problem is manufacturers. They can't even maintain consistency in their own size 6 jeans because the pieces are cut by machines that cut giant stacks of pieces of fabrics; therefore the piece at the top of the stack is a different size than the piece at the bottom of the stack. Forget where I read that or I'd link to it, sorry.
People like us who are sized out on the upper end of some brands' size range AND people like Angie who are sized out of the bottom end of some brands' size range are just stuck having to put in extra effort to find things that fit. And it stinks.
Until there is some sense to clothing sizes, I'll stick to the brands that I know have consistent sizing or that I can speak with somebody who can help me pick the right size.
Edit: fixed a typo