I was half-way expecting this to turn out like the last thread about this topic, I'm glad to see it didn't lol.
Much like anything else, its subjective. It's difficult to explain how you feel like the opposite gender, you just feel it if that makes sense? When I was super young (think 5) it often upset me whenever people called me a girl and treated me as such, not to mention I always had thoughts like 'i wish i was/had been born a boy'. For me, there wasn't a point where i was like 'i feel like a dude' it's always been a consistent feeling/thought in my mind. I felt a disconnect with my body, as if I had just stolen it from some other soul and it was not meant for me.
I don't particularly go around telling people I'm trans however, even though now I am infinitely way more comfortable with how I present. It's primarily because it's just disgusting knowing people once knew me as a girl. I want people to know me as male and assume I've always been one. I don't like to be reminded of the fact that I was born female, nor do I want people to know about that fact either because it feels like I'm not going to be taken seriously and I'll be dismissed for not being 'legit', as weird as that sounds.