To a large degree, the answer to that is the fact that I grew up in the 60’s and 70’s. At that time the world was a lot less open to LGBTQ+ things than it is today. Although I had no idea I was trans, trans wasn’t even a word back then, I somehow knew what I was wasn’t accepted.
Boys were supposed to do “boy things” and girls did “girl things”. This much I knew for sure. If I was to express that I wanted to do girl things it would not bode well for me and I knew that. At a minimum, I would receive a lecture. Depending on where I was it might well result in very cruel jokes and likely physical abuse. So I kept those feelings to myself.
I think this was made even more intense by my Grandfather. I loved him very much; he was the best man at my wedding. He was also the cruelest bigot I have ever known. He would make such malicious comments about anyone who wasn’t just like him. I think this reinforced my feelings that if you were not “normal” you were rejected. So I hid all of my differences until even I barely knew they existed.