[DDtop]

I've noticed that it also depends on the manufacturer of the bra. I'm also a 42b wearing a bali but waycoff or Playtex  it seems 44a fits better.
From my understanding if you go up a band size you drop a cup if you go down a band size you go up a cup.  
But style also has a lot to do with it.  One brand and style is not the same fit in another brand, if that makes sense. It's almost like buying jeans just because Lee brand size x fits well . Wrangler size x is to small or to big .

Hi that was what i was saying it's also the fabric content also as some have more/less elastic