Here is a link to a PDF that talks about the specific levels of severity (on page 6 in a blue shaded area). Keep in mind that, while the DSM provides a description of the different levels, the descriptions relate to subjective criteria as observed by the diagnostic professional (meaning there is a LOT that is left up to personal interpretation).
Also, as another article on the subject points out, severity varies from day to day and situation to situation. In the structure and/or relative sensory calm of a therapist's office, severity may appear less than in actuality.
Severity is split into two categories: Social Communication (SC) and Repetitive/Restricted interests and Behavior (RRB). A person can have different severity levels in each category.
For example, I would originally have called myself a level 2 in SC and a level 1 in RRB, but after reading the descriptions, I fit into level 2 for each. If I'm stressed or pressed, I become a full-blown level 3, and on the Internet, where I can type my interactions and think about what I want to say, I'm level 1 for SC. My therapist would probably call me level 1 because, to tell you the truth, I haven't been entirely honest with her. I haven't lied, just haven't told her everything.
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You don't need to hide, my friend, for I am just like you.