Alright, not a huge change, but as you mentioned, there are already so many things affecting lactation that "Milky" doesn't really make much of an impact. However, I made some changes that should hopefully be noticeable.
When choosing this perk in character creation, it'll give a slight head start to the milkMultiplier (+25) and increase the milkRate (+5). I didn't want to cause instant lactation because part of the "causes lactation to be induced more easily and harder to stop" should be about the character going through the process of developing the ability to lactate for the first time, so giving it away for free didn't seem like a good change.
I did think about adding a passive milkMultiplier increase over time (if milkMultiplier was below 50 or so), but that would end up defeating the purpose of the milkMultiplier degrading for not milking often enough (there are rules for degrading less when the character has "Milky" and/or "Treated Milk").
Using the "Milk Squirt" should now give a slight 50% boost to tease damage if the character has the "Milky" perk (due to more milk being expressed). However, keep in mind, after all the bonus multipliers, that tease damage caps at 200% its base value, as well as other modifiers based on trip/stun/etc. status, so is to not be too powerful.
When using the "Drink Milk" ability, if the character has "Milky", and milkFullness is at more than what is milked, the healing value will increase by up to 50% (due to more fluid being expelled), so this may be more of a perk synergy. Similarly, there's a "Breastfeed" attack towards a targeted enemy (but I'm not sure if that's been or ever will be implemented) that should go through the same rules.
More changes may develop later. I'll try to run it by the team to see if a rework is in order.