You need a new psychiatrist. That kind of unpredictability in treatment and appointments is harmful. I am a champion for psychiatrists, normally. I write and speak about the psychiatrist-patient relationship regularly for patient groups and readers. They practice a very difficult and small branch of medicine. They are badly needed. There aren't enough of them. They are underpaid and work under difficult conditions. However, your psychiatrist has an implicit contract with you. He has to do his part. At a minimum that means keeping appointments and being consistent fulfilling his obligations for your care. You have every right to be angry and every right to look for another MD.

I'd write him a respectful but honest letter telling him exactly how his mistreatment has effected you. Maybe it'll motivate him to perform better at his next job and give you some closure so you can start fresh with someone else.