Yikes. Well, I'm not sure how to label myself, but I can say I'm not "overly obsessive". I have two children (23 months apart) so I hope my opinion helps. First of all, I'm not sure what you want advice about. How to tell people you don't want more kids or whether or not to have more kids. I'm guessing it's the latter.
It sounds like your concern about having more children is based on your ability as a mom and a person. Can you handle it? Will you fail? Will you have to change your rigid ways? Well, I think the answers are all, yes. We all fail at times, it's natural. You did research, but you didn't get a customized manual and as far as I can tell, experts can be wrong and they don't know your child. Heck, they change the rules every few years (back to sleep, when to feed solids, etc). As long as we parent with love in our hearts and truly try to raise them to be good people who understand right and wrong as well as compassion and try to give them a desire to try to succeed, they'll turn out fine. My parents did a lot of things differently, because that's what the experts said to do and I survived. (something to consider when you think about the necessity for your "overly academic approach", when will the experts change those rules?)
I have a friend who is rather rigid. She has a schedule and keeps a schedule. Everything has a place and every day is planned at least the day before. Result, her child (who granted probably was born with some gene predisposing her to this way of life) has jumped off the deep end. She has a fit if a "downstairs book" ventures upstairs. She comes unglued if a playmate puts a babydoll in the wrong carriage. She gets up every morning and asks mommy for the plan for the day and gets upset if it isn't complete. Everything they do is a ritual and it must be the same. The mom sees the problem that's been created and is trying to be more relaxed in hopes of helping her child relax but as you can imagine, it's hard.
I'm not suggesting your child is like this, but you should consider that children learn from their parents. They pick up habbits, learn worries and stress and immitate. I am guessing that your still pondering having more children or you wouldn't have bothered posting here. It would be easier to just tell people no, we're not having more. So, I think you should look for the positives about having another child and then decide what will make your whole family environment happier. The answer could go either way. If you're not on board, I think it's a bad idea. Here are a few positives, but there are many more...
Baby "A" will have a playmate at all times and also someone to argue with. This may try your patience, but this presents an opportunity to teach them how to build good skills to resolve disputes. They will have to learn to share and wait their turn to speak and be a good influence. Sure they learn some of this at school, but they often act differently at home. They will learn that life isn't always fair and it's healthy to know this before you're an adult.
Also, you will have an opportunity to not be so rigid. Life gets a little more unpredictable with a second child... mainly because they are different personalities and you think you already have it all figured out with the first one. Perhaps you are past the diaper routine and you feel like you know what to expect from your little one and how to handle it. Perhaps you are concerned about handling two different age ranges (loading diaper bags and soccer bags... looking like you're going out of town instead of to a 2 hour soccer game). Rigid people need to relax and be more spontaneous and enjoy the moment. Spontaneous people need to learn to plan, be organized and be on time.
I think having a second child is a very exciting and scary thing. Life is a little hard for the first year (especially if the older one is less than 3). It's hard to go back to getting up at night to feed the baby and changing countless diapers... remember what those days were like? Now think about what the current days are like and how great you older child is. Wasn't it worth a short time (in the grand scheme of things) of difficulty to have such a great little kid in your life?
I think people who don't want children should not have them. I think children should be brought up in a loving household with parents who want them and cherrish them. I think it is so important that you be honest with youself and make an honest decision. Don't make a decision based on guilt or what other people think. Your child(ren), husband and you will all be happiest if you make a decision that makes you happy.
Good luck. I hope this helps.
Liz
p.s. As for child care, I'm a stay at home mom so it's hard for me to comment. Perhaps you can find a home care situation with less children.