I had florid psychosis in and a somewhat lighter form of it in 2016. I could not tell that I was psychotic until afterwards.

A bad self image is very common and psychosis is relatively rare. So statistically, chances are that a bad self image does not mean that you are psychotic. Also, psychosis in bipolar people is episodic whereas your bad self image is something you have always had. This, too, argues for "bad self image is not psychosis".