Most of us--if not all--are not poly because we feel poly. We are poly because we simply love more than one person at a time.
For me, I found when I was first getting interested in girls that I was always interested in more than one. Even when I made a connection with one, I was still interested in others and could connect with them, too. I wasn't terribly interested in the "going steady" thing because it meant I couldn't also see other girls.
Did I feel poly? Um, no. Leaving aside the fact that the term hadn't been coined at that time, I only knew that I could love more than one at a time. I wondered why it wasn't possible to "go steady" with two or three girls.