What you're describing seems like the introversion/extroversion distinction, which is probably different from, although possibly overlapping and somewhat correlated with, the autism spectrum/NT distinction. The introversion/extroversion literature seems to capture the difference pretty well; just about everything I've read about introversion recognizes that introverts can be competent to excellent at one-on-one or small group socializing, but that they are probably less good and certainly uncomfortable in large group settings. But I don't recall reading much about introverts that suggests they're unable to read social cues (although they may have less practice at it as well as less interest).
I haven't seen a breakdown on introversion/extroversion numbers in the population (my own quick Google search found an article in the Atlantic with this passage: "How many people are introverts? I performed exhaustive research on this question, in the form of a quick Google search. The answer: About 25 percent. Or: Just under half. Or—my favorite—'a minority in the regular population but a majority in the gifted population.'"), and as NancyLebovitz also suggests, I believe it varies between cultures, but what numbers I have seen seem to suggest that the percentage of people who fall more on the introverted side of the scale is probably considerably greater than the percentage of people who fall on the autism spectrum.
It's certainly possible that neurotypical people misunderstand autism spectrum people, and that extroverts misunderstand introverts (the Atlantic article makes that argument), but the autism spectrum descriptions about not understanding social cues seem to be getting at something real and different than introversion. Your description makes you sound like an introvert but not particularly far along (if at all) on the autism spectrum. It does seem like some of our commentary here may sometimes be casually conflating extroversion with neurotypicalness and introversion with autism spectrum.
About 25 percent
I believe that is a US-specific figure
Followup to: Do you have High-Functioning Asperger's Syndrome?
LW reader Madbadger uses the metaphor of a GPU and a CPU in a desktop system to think about people with Asperger's Syndrome: general intelligence is like a CPU, being universal but only mediocre at any particular task, whereas the "social coprocessor" brainware in a Neurotypical brain is like a GPU: highly specialized but great at what it does. Neurotypical people are like computers with measly Pentium IV processors, but expensive Radeon HD 4890 GPUs. A High-functioning AS person is an Intel Core i7 Extreme Edition - with on-board graphics!
This analogy also covers the spectrum view of social/empathic abilities, you can think about having a weaker social coprocessor than average if you have some of the tendencies of AS but not others. You can even think of your score on the AQ Test as being like the Tom's Hardware Rating of your Coprocessor. (Lower numbers are better!).
If you lack that powerful social coprocessor, what can you do? Well, you'll have to run your social interactions "in software", i.e. explicitly reason through the complex human social game that most people play without ever really understanding. There are several tricks that a High-functioning AS person can use in this situation: