Pandemic lbs got my cups up to a K so currently shopping for a whole new wardrobe and only a 4XL bikini top fits right now. It was easier when I was just an H-cup 😩 . I used to be a Bra Fitter and as someone with a 30 band back with fuller cups (12 D cups=K) band conversion isn't always a good idea. It works cup wise at times but the support is lost when the weight of the breast tissue is transferred from your back to your shoulders which is partly why women, like myself, tighten our straps and our bras ride up in the back...it's because the band is too big. . There could be other reasons for a bad fitting bra, the above explanation is
regarding me trying to substitute a 30K