The center piece between the cups should sit flat against your breastbone. If it’s hovering, the cups are likely too small.
Your breasts should fill the cups without "quad-boobing" (spilling over the top) or gaping (extra space at the top). how to buy correct bra size
Numbers are just a starting point; the mirror tells the truth. Look for these signs of a good fit: The center piece between the cups should sit
When you put on a bra, lean forward and use your hands to pull all your breast tissue from the sides into the cups. This ensures you’re actually sitting in the bra correctly before you judge the fit. how to buy correct bra size