If you’re a woman with any ‘A’ cup you’ll find the majority of traditional bras rarely ever fit. Even the ones I’ve purchased in my ‘A’ cup size do not fit completely right, and tend to be uncomfortable most of the time. I don’t think I’ve ever had a traditional ‘bra’ I’ve ever loved.
I’ve started using Bralette’s instead. There are some fairly simple designs that work as replacement for a ‘Bra’, they’re much more comfortable and actually do what they’re supposed to do, and some bralettes are padded as well.
Overall from my experience (and observation) a bralette’s purpose is to be “fashionable” in hot weather by women who choose to forego a top, but far more importantly they serve as a functional option for women who have small breasts.