How do I know if my bra fits properly?

The gore (the piece that joins the two cups together), should be sitting flat against your chest cavity, not sitting away from your chest cavity by an inch or two.

The wire should be at the back of your breast tissue, not pinching it.

Ensure the band is sitting across your back, horizontal to the floor - not riding up your back in a u-shape.

When you reach your arms up in the air, the bra should not be riding up your on your breasts.