I know exactly how I feel. I'm reasonably certain there's an actual medical name for your situation, complete with books specifically related to the subject, but I don't want to sound insulting if I say it. I know, because I fall under the same category. If you're looking for a more detailed description, shoot me a PM and I'll give you my thoughts.
Through my research, I've found there are two groups of people in this situation.
The first are people like you; nice, happy to let others take control, perfectly happy following rules because they add structure and order to an otherwise chaotic world. That don't have to make a decision for the lesser of two evils, and instead do exactly as the book says. This is fine for much of life, and many of these people find comfort in joining some form of military; strict discipline, no room for interpretation. Bliss for those that follow. However, when it comes to social interaction, problems arise. In a social setting, there are no rules. It's every man for himself, survival of the fittest, the first to the egg wins. With a total lack of predefined conversation, even talking to people is difficult.
The second are somewhat different. They believe that true power resides in strength, and showing no weakness that other people could exploit. I won't go into detail about it, but suffice to say they tend to be a little aggressive.
My advice to you (it sounds harsh, but I don't mean it to be): stop caring. Personally, I over-analyze everything. Every word of every conversation I've ever had has been spin dried and hard washed in my mind dozens of times. It led to severe anxiety, which doesn't help at all. I've found that the thought, "I'm never going to see this person again, and even if I do... what could I possibly say to make them consider me the spawn of satan?". It's actually a recent revelation, but it's made a huge difference in my life. People I couldn't stand to know were alive a few years ago have become good friends, casual conversation is much easier, and people seem to freely speak to me now.
With that out of the way, time for some generic advice.
Prepare for smalltalk. It never made sense to me why people would talk simply because their vocal chords made sound until I started with the cliche'd ideas to help a conversation flow smoothly, which is the singlemost important thing to do when talking to someone. Try to avoid any pause longer than about five seconds with casual things like, "The damn weather can't make up its mind", average things like, "Man, I wish the game of (insert activity here) went better", or personal things like, "Nice shoes, mate. I've had these boots since the stoneage, complete with the craftsmanship. How do those fit?". Anything else can fit; as long as you say something to provoke a response, regardless of what you actually say, you'll find it's easier to chat. "Keep the flow, bro" is my life motto.
You'll find that some people don't want to respond, or do so in a really lackluster way. In that case, screw them. They aren't worth talking to and probably don't have anything intelligent to say anyway.