You can't judge whether a bra is the correct size for a woman when she has her arms raised. That is
not how one stands when getting measured for a bra. For good reason.
Your name on your profile is Roza, which is a girl's name, so I'm going to assume you are of the female sex. Your comment displays a phenomenal lack of awareness of the female anatomy. When you lift your arms up, the ligaments in your breasts pull up the rest of your breasts so that they look "flatter". I encourage you to do this in front of the mirror, with and without a bra.
In case you think I am joking, this is one of the reasons why doctors do a breast examination with the arm of the woman raised as in the image in Step 4 here:
www.breastcancer.org/symptoms/… .