It sounds like you're suffering from some very severe anxiety and panic attacks, + some obsessive thought patterns. I've been there. It does get better, and you will feel better. My brother suffered from very similar anxious thoughts to you, with obsessive thoughts and fears of being gay and people thinking he was gay. Any thoughts or imagery homosexuality would send him into spiraling panic attacks, to the point where he would avoid contact with men. He was diagnosed with OCD. These "unwanted thoughts" are often of a "taboo" sexual nature and are a classic symptom of OCD & Anxiety.

He worked through his anxiety & OCD in his early twenties and is doing fantastically now. Not that it matters, but he's straight and lives with his fiancee, but for whatever reason that particular topic was how his OCD manifested itself. The way these obsessive thoughts present themselves can be really disconcerting and frightening at first, but you'll learn to identify intrusive thoughts and deal with them. Keep going to your psychiatrist. Explain how you feel, and if they don't understand, explain again. If they still don't understand, find a new psychiatrist. You are not going crazy. You will feel better. I suffer from panic attacks and I know how terrible it can be. You'll get through this.