I wonder what size bra she wears
I’ve done a bit of research on her, looking through her various pics and figuring out what brand(s) of bra she’s wearing. The best example I can find is Curvy Kate Victory (black) - which goes up to a K cup (pic attached). I’d estimate her to be just over 5ft tall (about 5’3”) - and with quite a broad back. Looking at it closely, the centre gore is coming away (you can see the shadow) and the shoulder straps are stretched to the max and angling inwards across her body over her shoulders towards the nape of her neck at the back (on a properly-fitting bra they would go straight over her shoulders vertically - it’s possible they’re being pulled together with a fastener to give her more support for the purposes of the photoshoot). I’d have to see her back band, to see how low it is, but I suspect it’s curving up or riding high on her back and not low and horizontal across the middle or lower back.
With all this in mind, my guess is (based on her frame size) that she’s wearing a 34K - it would give her the biggest cup size for her shape, with reasonable support - but she looks like she needs a 34KK or 34L. In some of her other photos, she’s wearing brands like Nessa and Ewa Michalak, which tend to fit bigger, and often come in bigger cup + band sizes.
I’d say she’s probably a 34KK or 34L, at least.