From my two years of Latin long, long ago, I was vaguely aware of the fact that 'ego' isn't needed.
Spanish (which I know much better) is the same - ie. 'Donde soy?' is all that's needed but for emphasis one can say: Donde soy yo?
I was also unsure about the question mark in Latin. After a little search I learned that it dates from the 8th century A.D. So, it didn't exist in the Roman 'Golden Age'.
My interest in the phrase: 'where am I?' comes from a talk I recently attended having to do with 'mindfulness'. Asking the question, 'where am I?' was described as a means or a device to 'turn one's attention to the moment'.