How do judge the quality of your own PhD?
You can't.

Probably this is a bit strong, but I think that in general you can not grade or judge your own thesis or assess its quality in any way. You are hopefully very critical with yourself and this is good. Your advisor and others referees for your thesis can and will grade your thesis and should provide a report which you may be able to read (depending on the local regulations) . If you need a more detailed feedback, ask these people some time after your defense (not directly after your defense - after passing it's time to party...).