Look at the shape and appearance of your breasts and nipples in the mirror with your hands by your sides. Raise your arms above your head and have another look.
Lurve your pair by having a good feel. Feel all of your breasts and nipples looking for anything that isn't normal for you. Feel from your collarbone to below the bra-line and under your armpit too.
Learn what is normal for you! Breasts come in all different shapes and sizes, so get to know your normal. See your Doctor if you notice any changes.