Chiropractors are not doctors. You should read the evidence based book Trick or Treatment, it is an amazing book debunking false medicine (acupuncture, chiropractors, etc) and very informative https://www.amazon.com/Trick-Treatment-Undeniable-Alternative-Medicine/dp/0393337782
This might not be exactly what you are looking for but I would recommend - Trick or Treatment. It does a good job at explaining the scientific method and how homeopathy, acupuncture, etc have been shown not to work in multiple studies.
I really like this book because it fairly balanced in its analyses (tho' I am sure there are people who think homeopathy works and could pick faults in the book). Also if you want to scientifically honest, the book is good starting pt to think about how certain we are that some things (e.g. homeopathy) are completely useless while others (e.g. acupuncture) might be useful in some cases - even if the underlying stuff about chi, etc might have nothing to do with actual physiology.
>and do see a chiropractor occasionally. I don't do homeopathy or anything like that
Actually, you do. Everyone should read this: http://www.amazon.com/Trick-Treatment-Undeniable-Alternative-Medicine/dp/0393337782/ref=sr_1_1?ie=UTF8&s=books&qid=1286840592&sr=8-1
Simon Singh wrote that book, I highly recommend it
https://www.amazon.com/Trick-Treatment-Undeniable-Alternative-Medicine/dp/0393337782
You should check out the book Trick or Treatment by Simon Singh and Edzard Ernst. It goes through the history, theory, and scientific evidence for a variety of alternative treatments including Chiropractic, Acupuncture, Herbal medicine, and more. It's a good read, but the tl;dr version is that there was some evidence for acupuncture as an effective treatment, but as the research methods improved, it's looking more and more like it's no better than a placebo.
Incidentally, Chiropractic doesn't fare much better. Chiropractic is really pseudoscience, though some recent chiropractors are using only the more effective parts of chiropractic and jettisoning the rest. (Some chiropractors still claim to be able to treat all kinds of diseases and ailments - not just those related to the back/spine even though there's no evidence to support this.) If your chiropractor is a true chiropractor, you could be at real risk of doing significant damage. Even if they're one of the "good" ones, you're probably paying too much compared to what you could get from a real doctor.
An interesting aside: libel laws were (are?) extremely harsh in the UK. When Simon Singh started talking about the evidence of chiropractic, the British Chiropractic Association in the UK sued him. Had they won, Singh would have been personally liable for millions in damages. After the dust settled, Singh won and chiropractors in the UK are now forbidden from claiming any efficacy in their treatments. Here's an interesting Wikipedia article about all of that, but there are even more articles online.
http://www.amazon.com/Trick-Treatment-Undeniable-Alternative-Medicine/dp/0393337782
A good discussion of the various alternative treatments, and the various meta-analyses performed, along with discussion of the origins of the scientific method.