Here is my save got her stats really high on bum. Pretty much all the grinding already done... Panties stuck on 12/20 for some reason? Can't seem to get more...
Late reply, but for people trying to get the 20 panties achievement, they are super buggy. I was repeating weekly routines to maximize panty-hunting opportunities (skipping sex/talking, working on chores multiple times on weekends, always bathing alone so you could laundry-snoop during her bath), and often I would have repeats of the same panties I'd already found. I worked my way up to 15/20, and suddenly the next day began with the 20/20 event.
I'm assuming there's a counter that takes tally of all panty finds, regardless of duplicates, and once that triggers, you'll have them all unlocked, even ones that you didn't discover through searching. I can't think of any factors that would've created this bug that I was in control of.
I used Cheat Engine for money, trust, sexual interest, and for locking the hours during sex/bath events, but nothing that should've impacted the panty count.
I did try to save before initiating daily baths a few times, which confirmed that the outcome of which panty found, if your sister catches you, and if anything turns up during your search is randomized after initiating the bath, so it was different every load.
Also, I haven't had the opportunity to try it yet, but not sure it'd even be worth it, since a few posts imply there's no alternate pregnancy outcome besides the two people have found, but I (am/going to be) disappointed if there's no exclusive outcome for getting to 100 days without impregnating her, sharing that confession of wanting to spend the rest of their days together, and then being able to knock her up.
What's the point of condoms being an item if all it does is delay one of the four parts for the full ending? It's basically necessary to have a pregnancy scare, and then she simply can't get pregnant after that event happens.