The definition of a mental disorder is a chemical variance in the mind.
No it isn't.
I'll quote the DSM for a proper definition:
"A mental disorder is a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotion regulation, or behavior that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning. Mental disorders are usually associated with significant distress or disability in social, occupational, or other important activities. An expectable or culturally approved response to a common stressor or loss, such as the death of a loved one, is not a mental disorder. Socially deviant behavior (e.g., political, religious, or sexual) and conflicts that are primarily between the individual and society are not mental disorders unless the deviance or conflict results from a dysfunction in the individual, as described above."
Basically, it's any pattern of behaviour or thinking that impairs functioning in daily life. Medically speaking, a mental disorder may be caused by a
chemical var
iance in the mind, but that in itself is not a definition. So no, just because there is a chemical variance doesn't mean we all harbor some kind of mental disorder. It is when these reach an abnormal level and cause problems that someone can be said to have a disorder.
There are mental disorders that deal with emotions, namely those classified as mood disorders. And no, these are not misinterpreted emotions. Emotions exist on a gradient, and let's look at the happy-sad one since that's the simplest. I'm sure most would agree that being happy or sad is perfectly normal. It's when these are taken to extremes that they become abnormal. Being so excessively sad that you want to kill yourself would likely be a disorder (depression). On the other hand, being so excessively happy that you decide to try your luck at gambling every last dollar you have would also likely be a disorder (mania). This is a trend found in basically every mental disorder. We all have quirks or tendencies that may be characteristic of certain disorders, but unless these reach extreme levels that disrupt our daily lives, they are not mental disorders. Rather, they are the variations that make each of us unique.