But I did ONLY major Chick choices in both my playthroughs, I don't know where I fucked up but I'm was pretty sure I did everything right.
Well, time to replay the game... AGAIN.
Just to make sure we mention the obvious, in addition to CHICK affinity, you also have to choose to shower at the same time as Jill. Initially you can make a joke or offer to let her shower first, but Jill will say that's silly. After some banter, you'll get the actual choice:
Showering with Jill still has the MC in a separate stall, but it will give him an option to accidentally fondle Jill in the shower. More importantly, it gives the MC the chance to kiss her once they are out of the shower, which is my favorite Jill moment to date.
Also, as a scarred veteran of many an old adventure game, I can't recommend enough the mantra: Save early, save often,
save in multiple slots! BaDIK is nowhere near as fond of unwinnable game states as the King's Quest series, but there is a lot of content you can miss out on. At a minimum, I'd recommend keeping a save at the end of each episode.