pre-everything, so maybe i'm not qualified to join in this topic, but i'll throw my two cents' worth of experience in anyway:
i was raised to be a heterosexual female and not question it, so for a while i thought that was the case. i started noticing girls in middle and high school, but tried to ignore it; it was a while before i started to consider myself bi or pan.
some years ago, i had a huge weight problem due to some issues with medication. i had just gotten off of birth control, which had nearly killed my sex drive, and was having problems with another medication i was on around the same time. this put my hormones out of whack, and i had some very mild masculinization as a result (increased sex drive, loss of period, slight change of fat distribution, increased body hair, etc... i even gained a single little beard hair that now annoys the crap outta me lol). after that, i really started "noticing" things in terms of what i was attracted to. having a boosted sex drive for the first time since puberty and being away from my family, i was a little more free to explore what i liked--though i was in a monogamous relationship at the time, so i didn't explore too freely then, either. but some part of me had to acknowledge that if i were single, women would definitely not be off the table.
since then the relationship has ended, the weight problem has been resolved by changing medications, and the hormones are back to normal female levels, with the sex drive back to being very minimal. but i have had time to really look and think about what i find attractive without feeling the need to repress myself, and i've come to the conclusion that the only thing i know for sure that i'm attracted to is women. i'm not sure if i was ever really into men at all, or if it was just "then done thing". i can admire a good-looking man, but it doesn't really feel the same to me as when i see a pretty gal.
i'm hoping that when i do get to start T, i'll have a better grip on exactly how i feel about certain things. right now, it's hard to tell because i don't want anyone else to be into me as i am now, and i don't want to imagine myself or be put into a female role. but long story short, i think i've gone from being "straight" one way to being "straight" the other way. i don't know if that was always true and i just refused to acknowledge it for so long or if anything has actually changed for one reason or another over time.