1. The bra should it snuggly/tightly/firmly while done up on the LOOSEST set of hooks.
2. The band HAS to be even/horizontal to the floor/as low as the front at the back.
Elomi Lexi 8870
There is a little bit of an arc on this model but it is slight. The straps are extended and do not gouge her shoulders. The top edge does not gouge into the flesh below the armpits. The fit is pretty good. Every body will have a bit of compressible flesh that gets compressed or squidge.
Fantasie Julia 9162
Fantasie Ivana Rosewood 9021
A bra has to be snug at the back to anchor and support the bust at the front. If the band rides up it is now a sling and offering no lift what so ever. Often one needs to go down a few numbers in the band and up a few letters in the cup for a correct fit.The under wire must sit at the crease between body and bust. A 34DD is similar to a 32F but only in the same style. Every brand and style may fit in a different size.
One should own 5-9, or more, good and properly fitting bras as each day wear a different bra and wash it every couple times it hits the rotation or every time one sweats in the bra. This is especially true for sports bras. Be sure to hand wash only as even once in the machine is death to the material in a bra. The under wires get twisted and bent, even pop out and ruin machines. By hand washing you are extending the life of your bras and saving money. Foam or molded or spacer fabric t-shirt bras get creased and destroyed easily so keep the cups in the open position and be gentle with them.