I don't really understand the Cup Size Preference option. Obviously negative numbers reduce and positive numbers increase, but what does each "unit" represent?
I imagine it would be difficult to implement at this point, but IMO a better system would be Min - Max. This could be pretty straightforward, with each size in the "range" getting 100/<range>% (e.g. Min of A and Max of DD is a range of 5), or (maybe optionally) something more complicated with highest percentages in the middle of the range and reducing percentages towards the extremes. I'd particularly like the latter as it would lead me to choose a wider range.
Or maybe Preferred Min - Preferred - Preferred Max.
For example, say I chose
P Min - A
P - C
P Max - DD
Make preferred some percent (maybe user selectable) and allocate the remaining equally among the others. So if percent for preferred was 40%, that leaves 60% to be distributed equally resulting in 15% each.
If the preferred doesn't fall exactly in the middle such as with
P Min - A
P - C
P Max - E
The remainder could either be distributed equally among the remaining five for 12% each, or again divided in half to each "side" of the preference for A & B at 15% each and D, DD and E at 10% each.
Or again, an algorithm resulting in reducing percentages towards to the extremes.
Granted this is somewhat complicated and would require a good in-game explanation.
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As an aside, I also wonder about the min of AA since the Pregnancy Growth Limit can be configured 4 sizes lower.