I am a diagnosed case. It's been the one big challenge in my life for my entire life—I always knew I was different from normal kids except I just couldn't put my finger on why and therefore couldn't solve the incongruencies. The real disenfranchisement was the diagnosis didn't formally exist in the diagnostic manuals (DSM) until I was around 15/16 years old, and medical science is largely in the dark as to the underlying causes and effective remedies. It wasn't until years later that I came across the diagnosis, after extensively looking through diagnoses in the DSM , to which no diagnosis adequately explained me until I found Asperger syndrome which described me with stunning perfection. But I dismissed the findings, since self-diagnosis is unreliable. It wasn't until I was 27 that I learned I probably did have it after all, and now a psychologist has formally diagnosed me.
Asperger syndrome is a mild form of autism but its effects, though relatively milder, can be very pronounced. For one, since the fusiform facial area of the brain is impaired, there is no reading of emotions in facial expressions, which causes impairment in lacking a theory of mind (intuitively understanding what someone is thinking). So, someone with Asperger syndrome (“Aspies”) unwittingly breaks unwritten social rules (which nobody bothers to tell you and you're expected to know) and behaves incongruently with someone's emotional state. Secondly, there is a kind of language barrier between how the Aspergic mind thinks and normal people, resulting in miscommunications and unnecessary arguments.
Asperger syndrome has its kicks, though. The obsessive nature of repetitive thoughts has given me a knack for in-depth research and having cyclical obsessive hobbies and interests has lead me to enjoy learning many things. Interests are focused and cyclically obsessive: I'll get obsessed to learn everything about something, and then after a week, month, year, or whatever I'll drop it for the next thing. In other words, it's like love. “Aspies” fall in love with things rather than people. Luckily, many of the negative effects can be mitigated by self-awareness, education of body language, and changing habits.
People with Asperger syndrome have the capacity to lead functional normal lives, so it's unsurprising your classmates would be surprised. As for misdiagnosis, who knows. Diagnoses are complex and share overlapping traits with other diagnoses, there are mild to severe cases, so only medical experts can address the question.