Everyone keeps screaming pregnancy every single time there's a scene but I feel like LM won't include pregnancy YET if that character's pregnancy would interfere in their role in the story. Cass and Lia both being unmarried would raise a few eyebrows if they got pregnant and Cass is a fairly active and physical character who is capable of fighting. Getting her pregnant would essentially bench her. We'll probably get pregnant Cass later in the story but right now is a really bad time for it
I fear you may be spot on for Cass; her pregnancy probably won't be realized anytime soon due to the nature of her character.
However, the drama is what makes this game so good: if LM decides to avoid all of it by leaving the pregnancies until the very end, that would be a cheap move.
The game is already promising one "major" time skip for CH2, so it's not out of the realm of possibilities that all the girls get pregnant "early on" in the story, and simply use a timeskip to a few months after the births where they can become active characters again.
LM promised us we would get to interact with all of the girls we get pregnant; and since he also seems to be aiming for AT LEAST 2 CHAPTERS, I seriously doubt Lia, Seraphina, and Cass are not going to get pregnant well before the actual end of the game. Just use timeskips to skip over the last few months of pregnancy and let us see our concubines with our children.
The drama writes itself.