I had a sudden weight gain, an absent period, and a few other symptoms, which was initially mis-diagnosed as Polycystic Ovary Syndrome. Despite treatment, I continued to gain weight. A year or so later, my father saw a local news health segment which profiled a woman with a rare disease, Cushing's Syndrome. My father called me into the room and said, "I think this is what you have."
I went to a new doctor (a PCP), who, without ordering a single urine or blood test, told me that I didn't have Cushing's because "it was too rare." Even though his exam of me revealed very high blood pressure. He bullied me into joining a study on anxiety and depression and a urine test for the study revealed high cortisol levels and he STILL insisted I didn't have Cushing's. He instead referred me to a neurologist for early-onset Parkinson's. The neurologist told me that my PCP was an idiot, and told me to contact an endocrinologist.
I had to wait several long months for my endo appointment, and before I got through three of my twelve bullet-points (yes I had them typed out, along with a "before" photo of myself), he said he'd never seen a more textbook case of Cushing's.
So, that's my story. My advice to you is to seek out an endrocrinologist (if you're lucky enough to not need referrals for insurance). You might have it, you might not but first you need a doctor who is willing to even consider testing for it.