Hiya, it’s difficult to say really as i think their decision depends on your natural breast width and a few other factors. Sounds like you have a slight frame, so that sounds about right to me with the 260’s..
I’m a 34D, i’m 5 ft 7 and size 8 on top, 10 on bottom. I’m having an uplift and implants but they picked 325cc Inspira mid projection implants which should take me to a decent full E cup, i wanted the extra projection to give me a good cleavage. hope that helps xx