Why** clothes buying is a minefield, I think Eva Musby covers it a bit in her books but I would go with a size bigger than you think and keep an eye on clothes that might be getting a bit small.
Interestingly dd said she thinks she's a size 12 now but seemed okay with it, she also chucked out a couple of pairs of size 8/10 jeans without a melt down.
She is tall, with broad shoulders so I think naturally fall in a size 12/14 as an adult (the same as me!)
I think her anxiety levels generally are okay at the moment so it makes these sorts of issues easier ti deal with. A year ago she would be screaming and self harming at finding her clothes were too small.
She's started a new job at Primark today which I'm praying is going okay!