Everything Under the Moon

Okay I was in high school and my science was talking about the third eye
she was fun teacher. she told look in mirror and third eye
I knew where it was. I did that I seen myself as who I was in the 1920's
Wearing black dress and feathered head band.
It kinda freaked me out .. but I knew my feelings were real.
I see my past selves in the mirror now and again

Nice. Decade ago I heard about this "scary" technique:
Stay in a dark room with only candle lit by the mirror and gaze into it long enough that you see your face changing into shapes of your previous incarnations. Should be changing into many shapes throughout ages.

With your recurring of 1920' perhaps you need to look into what stayed unfinished in that life's endeavour.
Wish you best of luck

A tip for better sight of spirits: When looking into mirror to see how you're groomed don't just observe yourself narcissisticaly, but also imagine a spirit (already present) to be standing there by your side. Look into mirror as if to see it right there.