Here are a few telltale signs that you may not be: wrinkling in the cups, underwire poking the sides of your breasts, a band that rides up, cup spillage, slipping straps, or a bra that hikes up when you lift your arms, says Sandi Simon, a fit consultant at Bra Smyth, in New York City. (Keep in mind that certain factors can cause you to change bra size: a weight gain or loss, a new exercise regimen, pregnancy, and a change of diet, among them.) If you suffer from any of the fit issues above, head to a professional bra fitter—or bust out the measuring tape and follow the steps here.

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