Pigtails, it sounds like these women just don't really interest you and you feel like they "should" so you can be "normal". I think your reaction was more normal, I'm bored, I can't relate to most of what these people are talking about, and why should I be here? I do agree that you may have some valuable things to say re adoption, or work, and you should respond if you have something to contribute. That's how they get to know you, and you would probably feel more included. Maybe you can find another book club with more like minded people.
I joined a club to meet people years ago and couldn't relate to most of them at all. I could make small talk, but it felt like a waste of time to be going to the activities because I wasn't having fun. I met one very good friend there, and we ditched the group and are still friends to this day. You may have to try on different things until you find a good fit. There have to be some stable and "normal" women in your area that still like to have fun!