How shall I report my education and calculate my GPA?
Since your university does not calculate your GPA, you should also not calculate a GPA unless you are told to. Most people do not care about your GPA from graduate level programs. As for reporting the PhD work, it really depends on what you did. Assuming you passed all the university requirements to be actually a PhD student, some universities require you to pass qualifying exams before you are actually a PhD student, you can list the PhD if you want. If you always intended to take the Masters and quit, you don't have to list the PhD if you do not want to.