Think of your bra band like a trusty pair of jeans. If your jeans slide down every time you walk, you’re constantly pulling them up. Same with your bra—the band should do 90% of the work, not the straps.
Try this: when you put on your bra, see if you can comfortably slide two fingers under the band in the back. If you can fit a whole fist, honey, that band is on vacation. You need a smaller size.
On the flip side, if the band digs into your skin and leaves angry red marks after an hour, that’s your body waving a little white flag. Go up a band size or use an extender—your soul will thank you.