There are SO many bra styles these days, all providing you with a different shape. You may prefer a more 'projected' shape, which projects your bust forwards instead of the sides, or you may prefer a 'rounded' shape, where the bra distributes your bust more towards the sides.
Ideally, we aim to lift your boobs as much as we can. Having a firm band is crucial for uplift as the band is meant as an anchor around your ribcage and not should move around as you move. A band that is too loose will ride up your back and your boobs will start to droop.
Once we have the correct size of bra it is important to determine what function you want from the bra. Do you need an everyday bra for general activities, a high-impact sports bra, a sexy evening bra or a strapless bra? Once you have established the style you need, it will help narrow down your options.
4 CLUES TO A BAD FIT
1) Band Riding Up
The 'band' is the part of the bra that fits AROUND your chest. Most of the support (80%) from your bra comes from the band, so it should be firm but comfortable. It should be horizontal and not ride up at the back. If it is not snug enough it may ride up at the back as your boobs move down. Go down a band/back size, but this means you must INCREASE YOUR CUP SIZE in proportion.
2) Bulging out of the Cup
Your boobs should be completely encased in the cups, with a smooth line where the fabric at the top of the cup meets your bust. If your boobs are bulging at the top or the sides of the cups, try a larger cup size.
3) Front Wire not Sitting Against Ribgage
The wires at the bottom of the cups should sit against your ribs. If your boobs are too big for cups, they may push the underwire away from your body - therefore a sign that the cups are too small. A good tip is to fill the cups with your boobs ensuring no breast tissue slips under the wire, and if there is any 'spillage' at the top or size of the cups, go up a size or two. If you notice the wires are always bent, check that you are putting your bras on correctly. See 'Are you a Flipper'
4) Baggy or Wrinkling Cups
When there's a lot of space in the cups of the bra, this is a sign that your cups are too big, and you need a smaller cup size. Sometimes, you may need to try a different bra style if this happens.
A GOOD FITTING BRA
Good fitting bra from the Back
A band that is snug and firm should remain horizontal around your chest - without riding up throughout the day.
Good fitting bra from the Front
The 3 most important things to note are that a) the boobs are completely enclosed in the cups, b) the underwires sit firmly against the rib cage, and c) the straps are not digging into the shoulders.