PSA: a lot of people wear the wrong size of bra for them, let alone the wrong TYPE of bra/cup/underwire length for their breast tissue and appropriate lift/separation.

Save yourself the discomfort and either try and size yourself at home with a tape measure, or book a fitting at a store (if they're not free then don't go to them, that would be absurd). It's worth it to actually be comfortable in something that you wear all of the time and have to spend money on.