To recruit a member, you need to be a diaper club member, then talk to naoto to accept bringing in new members. Maybe you missied that flag. For now, there is only one NPC that you can recruit, but it will be my focus to increase that number.
Indeed, it can be hard to catch every little doors on the save system. i'll look into that.
Thanks for your kind words! this mean a lot to me. If you want to talk about game design, don't hesitate to mail me so we can chat about it.