Like as a child I liked "feminine" things and didn't show any symptoms of being transgender other than not liking myself and not knowing why. (Maybe I was just insecure? But the moment I started looking more masculine I began feeling better and more confident) I didn't care about myself at all as a kid, I wasn't bothered by anything, so that's probably why I didn't know at a young age.

I began experiencing gender dysphoria at 11 (Which is still really young).

So is a therapist going to say I'm not "trans enough" to go on hormones if I didn't have gender dysphoria at like... the moment of birth? What was your experience with your gender therapist?

A competent therapist (one who has talked to many different trans people and keeps upto date on trans issues) will know it's unethical to check off a list of what makes a person 'actually' trans. They'll ask about your childhood because they want to know if you have consistent signs that may suggest your trans; but that shouldn't be what all the sessions revolve around. They should take into account how you felt around puberty; what was school like; what was/is your social life like; how you feel about yourself now. Which is much more important. That's what my experience was like seeing a gender therapist. She only asked about my childhood in the first session.

I've seen 4 mental health professionals total getting various referrals for trans-related things. Every single one of them asked about my entire life that I could remember, from childhood through now. Getting as big a picture of your life as possible helps therapists rule out your dysphoria being a symptom of another condition.

I do not know the answer to this as I am waiting for my insurance to pull through so I can start therapy, but just wanted to say thanks for positing this. I've been trying to figure out how to ask this question on here for a while.

If it makes a difference, here's my short life summary list:
--Don't remember much before the age of 10 (female puberty started), depression/anxiety became worse
--My strict religious mom dictated my outfits (quite girly) and hair (super long) until I was about 12
--I always felt "off", but it didn't sink in that it was gender related until about 15
--I had high depression/anxiety crap for the next 7 years, and now at 22 finally attempting to deal with stuff

Basically, you're not the only one who didn't know they were trans* since birth, and I've read a bunch of other posts where people didn't know until they were older. Worst case, if your therapist doesn't believe you, you can always find a better one. I'd be interested in reading how your experience goes, if you ever feel like sharing on here somewhere. I hope your therapist is good, and good luck.

Er...my therapist never really asks me about any of my past, she's more focused on moving forward I guess. I told her I'm trans when I first met her and she just took me at my word, there was never any "proving", though there was some exploration of my feelings on the subject, just to be sure she understood where I was at mentally.

This should not be a problem with good therapist.  I dressed very feminine and liked both feminine and masculine things as a child and a teen--I just FELT "guyish" as I always described myself.  But I loved dresses and high heels and makeup and stuff.  If you feel really worried about it then you could always stretch the truth and say you were a tomboy, though I dunno that it's ethical of me to suggest that.  Truth is, I don't feel that anyone has a right to tell you whether you are "trans enough" or not, so the mere idea of someone doing that upsets me. I didn't have a problem, though, and I was very girly throughout most of my life, at least on the outside.  It was my personality that was masculine.  Just be confident and go in with the knowledge that you are going to get your letter, it's not your therapist's decision to make.  That's what I did and had no problems.  They saw I knew what I wanted and gave me that.  Knowing what you want goes a long way with many therapists.