Rest assured, this is relatively common in Night Terrors.
I'm 57 years old and over the last 30 years I have experienced five times waking up in the middle of the night not knowing where I am, not knowing who the man is in my bed (my husband of 30 years).
I am always dreadfully panicked and scared and I do NOT know or realize where I am.
most commonly though i experience amnesia on waking up I lay paralysed for a minute in the dark having no idea where i am who i am with and exactly as you described I have no idea at what time period I am in my life, i have to focus on an object to eventually bring myself round and understand where i am. My husband has woke up a number of times to find me staring at his face trying to figure out who he is.
A likely explanation is that you have woken up enough to realize you are awake, but the parts of your brain that fix your location are still deeply asleep.