If the wire is too tight or sits on the breast your cup is too small or the shape of the wire is not the right fit. The wire gives you the needed support from underneath and from the side. You should not feel it! The wire should not press on your ribs or push or rub on the front and on the side of your breasts. The end of the wire should separate your breasts. It should lie smoothly on your skin without pressure.
The upper part of the cup should lie flat against the skin.
The lower part of the cup should be strong enough to guarantee the needed support, especially for bigger sizes.
A frame also gives more comfort for bigger sizes, because of the additional support it gives under the breast.
Under the arm the bra should lie flat and the cup should contain the breast in this part.
The straps should be comfortable and not too tight or too elastic and the width should be big enough according to the size. The adjuster regulates the length of the straps. They should be positioned so that you cannot feel them, especially not on the shoulder blade. Put on an item of clothing over your bra and look from the front and from the side, to see the result matches your expectation. Some bras are very pointy, others are very flat and some of them push your breast up. Normally you can see it, when you are wearing an item of clothing. It depends on your own personal taste.