I think... that bounce is a factor of bust size. If bust exceeds the bounce, you get a card for every so much your bust is over the bounce.

So if you have 6 bust and 6 bounce, nothing should generate, but 7 bust and 6 bounce is 1 over, so it should make a card.

You generate a number of bounce stacks equal to your buxom rating each turn, the bounce limit dictates how much "bounce" you generate before you get the respective status card.

i.e. If after your first turn you're at 8 buxom and your bounce limit is 7, you'll generate a bounce status card, then be left with 1 bounce stack at the end of your first turn. If after your second turn you're at 24 buxom and still have a bounce limit of 7, you'll generate 3 bounce status cards, then be left with 4 bounce stacks.

Capacity will not stop your bounce status cards from showing up, it only factors into whether or not the bra is "intact" or not for the purposes of certain cards. The only way to mitigate your bounce stack gain is through lowering your buxom rating or using Omega Runes, which increases the bounce limit by 1 each time you use it.