@Abortions4All 's comment above describing the OCD-like symptoms of dysmorphia is correct, but some of it is also that the terms "dysphoria" and "dysmorphia" are so broad nowadays that half the population would qualify. Here's how Wikipedia defines dysphoria: "a profound state of unease or dissatisfaction. In a psychiatric context, dysphoria may accompany depression, anxiety, or agitation." That sounds like every angsty teenager ever. But now there's a psychiatric term that you can leverage to make your unhappiness go away, because Reddit says so.
IMO, a more accurate definition would be a sense of incongruity between how you perceive yourself and your actual appearance. Looking in the mirror and being disappointed or self-conscious because your boobs are too small or you have a gut is a normal part of life. Looking in the mirror and seeing someone you legitimately do not recognize as yourself, that's more serious. Very few people are 100% satisfied with their appearance, but that doesn't mean we need to label it as a disorder and hustle everyone into the plastic surgeon's office.