Please specify that you're using "Complex Breeding" mod. It is the source of your troubles.i have some problems in my modded game. i somehow dont get nekos. and i would like to have a tentacle room for enlargeing breast size and womb size but every upgrade is draining or enlargeing with negativ numbers. can someone help?
Base form of catgirls is "imp". Which can evolve into succubi or nekomatas under the right conditions.
With tentacles, there is always a price to pay. When "draining", you are paying the price. Positive number is how much you're getting in your "wallet" called "vitality reserve". When improving, negative number is how much you're taking from the "wallet" for each upgrade. Tentacles would not allow you to buy on credit, you have to pay first.
Finally, check "complex breeding" guide in my signature, it might help.