

As a cis guy, it feels pretty unnatural to say “when I was a boy” because the word has always meant gender more than age to me. Since the variable I’m indicating is my age, I use “kid” or “child” for it.
As to the broader question, my gut tells me to go with your gut. Whether the word “boy” or “girl” is what came to your mind, there is probably some relevant nuance to what it is you’re saying about your younger self that informed that instinct.
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