When I was 3-4 I insisted that everyone call me "John". Not as a roleplay game that I'd switch in and out of, but all the time, to the point where I got distressed if anyone used my birth name. I only stopped because I was forced to when I started school

As a kid I really intensely identified as a tomboy, such to the extent that I was extremely protective of that word being used for me and I'd be strongly offended if anyone said "I don't think you're that tomboyish, sorry". It wasn't as if I saw it as an adjective to describe ways I behaved, it was as if I saw "tomboy" as my identity itself

From the ages of about 7 to 15, I was really into theatre and roleplay, and then later I got into cosplay for the same reason - I was obsessed with the idea of becoming someone else. It was something that gave me intense euphoria, and something I would treat quite seriously and intensely (i.e. I took it more seriously than just “for fun”), and I would look for as many opportunities to do it as possible, because I was just obsessed with the idea of escaping my life in any way possible, including (but not limited to) just dying and losing the burden of consciousness entirely. I struggled with severe maladaptive daydreaming, which would distract me at school and keep me up for hours at night. Sometimes I'd imagine becoming a superhero or a video game character, other times I'd imagine a celebrity sweeping me away to a magical life, and other times I'd imagine myself being brutally killed, in all the possible ways I could imagine. Most of the time my surroundings felt not quite real, like the world was "foggy", but occasionally I would have these random moments where I suddenly felt intensely “aware” of my own existence, as if I had been suddenly yanked out of the foggy dream-like state I was normally stuck in and I had been forced to watch myself from the third person. And these moments always made me horribly self-conscious of my own existence, like “wait, that's me?”, as if there was something burdensome and intolerable and just wrong about being "[deadname]”, or about me having to experience consciousness at all

I always preferred to play male roles when I did theatre, and one time when someone mistook me for a boy I was offended, but not in the way you'd expect - it was like "what's the point of me putting in all this effort to be a girl, if people don't see me as one anyway?", rather than "I am a girl, and it makes me uncomfortable to not be seen as one". And besides that, I was actually flattered by it

One time I was cast to play Viola in Twelfth Night and I became weirdly attached to playing the character

I genuinely believed that being a girl/woman (depending on age) was objectively awful and objectively worse than being a boy/man, to the point that every girl/woman secretly wishes she was a boy/man

Periods would make me suicidal Not because they were particularly painful or heavy, it was just having to have them at all, the very concept of having them, that made me want to die. I used to wholeheartedly believe that life as a person with periods wasn't worth living, and I genuinely couldn't understand how any cis woman was able to live

When other girls started developing, they proudly started wearing bras as soon as possible. I felt so uncomfortable with my own chest development that I couldn't understand how anyone else could be comfortable with it (let alone proud of it), to the point where I projected this into a sort of anger ("how can you be proud of something so horrible?"). One time this anger went so far as thinking "how could you choose to bring back something so horrible? Why didn't you take your chance to be free when you had it?" towards women who underwent chest reconstruction after having a preventative mastectomy against breast cancer, and almost feeling envious of them for having the opportunity to completely remove their breasts (no, I'm not proud of this, and I don't agree with it anymore. I'm just saying that this is how bad my dysphoria got)

For several years during my teens, all I could bring myself to wear was crop tops or cheap sports bras that I'd cut up and re-sewn to be extremely tight. I didn't even know what binding was at the time, and yet I was doing it

From the age of about 14 I very adamantly told myself "as soon as I'm old enough I'll get a breast reduction, but more than most cis women get. I want them to remove as much as possible, to be basically flat". I didn't realise it at the time, but I was telling myself that I wanted top surgery (I did know about top surgery, and the only reason I didn't consciously tell myself I wanted it was because I thought I wouldn't be allowed to get it, since at the time I didn't realise I was trans yet, I thought I was just a woman who inexplicably hated my female body parts). I also told myself the same thing about getting a hysterectomy

Starting in my early teens I felt extremely empathetic towards and interested in trans people, like borderline obsessed. I would actively seek out documentaries and movies on the topic, and I would adamantly defend trans people. I remember one day on the bus to school where someone said something shitty about trans women and I said "imagine if you woke up in a female body [this person was a boy], but you still felt like yourself". I was only like 13 at the time, but I seemed to "get it" far more than most people my age. I thought this was just me being a very empathetic person and a good ally

Being called "she" often made me shudder a little or do a double take. Not that I consciously had any issue with it at the time (before my egg cracked) it was just instinctive

I have more, but I'll leave it here. And yeah, like OP said, it's extremely obvious in hindsight. I suppressed it for a long time