For example, sometimes people talk about lowercase "t" and capital "T" trauma. Lowercase "t" is when something affects you enough that recognizing it elicits an emotion, e.g. some people fell uneasy when smelling saline because they associate it with getting shots when they were young. Uppercase "T" is when the emotion is overpowering, e.g. soldiers who wake up screaming or experience lifelike flashbacks when they see military equipment, or people who can't visit a location without panicking because it reminds them of a negative experience. Only uppercase "T" is diagnosed PTSD, although that doesn't mean lowercase "t" is never a problem, it's just not life-altering and can be worked around without medication or therapy.
We have regular adjectives for the manageable "lowercase" version of disorders. "Obsessive" for OCD, "antsy" or "trouble focusing" for ADHD, "strange" or "peculiar" for Autism. I do think someone can be "manic" or "depressed" without having diagnosed Bipolar or Depression. Unfortunately, language is defined by how it's used in practice, so if most people call themselves "ADHD" when they don't have real diagnosed ADHD, you'll have to use their meaning to understand them, and eventually it'll become the norm; but you can speak and write the non-disorder adjective to help counter it. Worst case, we still have "diagnosed X" to distinguish from "X" (unless people start using it like "literally" to mean figuratively...)