The wire in your bra is digging in or poking you.
If you are being poked by the underwire, then your cup size may be too small and you will need a larger size.
The straps are digging into your shoulders.
You may need to loosen the straps. Or, your cups may be too small, pulling the bra downward and creating tension in the straps, you may need a larger cup size.
The band is riding up your back.
Your cups are too small, and you will need a larger cup size.
There is a gap between the cups in your bra and your bust.
If you are not properly filling out the cup, then your band and or cup size is too large and you will need a smaller size.
The straps are falling off your shoulders.
Most likely, your band size is too large and you will need a smaller band. If you are not properly filling out the cup, then your band and or cup size is too large and you will need a smaller size. It is also possible that your bra has lost its elasticity.
How bra sizes work
It's important to understand that the band size and the cup size work together. One of the most common misconceptions is that a D cup is always bigger than a C or B cup. In fact, a bra's cup size is dependent on its band size, so a 10D holds the same volume as a 12C.
For example, you are currently wearing a 14DD and you want to go down a band size but keep the same cup, you will need a 12E, not a 12DD, to accommodate your breasts.
If, on the other hand, you are wearing the correct band size but wish to try a different a cup size, all you need to do to is move up or down a letter size. (This is why it is a good idea to establish your correct band size first before moving on to the cups.)
Caring for your bras.
A bra should be hand washed or if you wash your bras in the washing machine, put them in a mesh bag to protect them from other clothing. Always use the delicate cycle in warm or cool water, and use a delicate detergent without bleach. Never use a dryer; hang your bras up to dry instead.
Berlei Curves Notice
Note: if you wore Berlei Curves styles as Playtex you must go up one cup size from the original Playtex version. IE, Playtex 18C = Berlei Curves 18D