Another memory I have is rather person, but I'll share it since you seem genuine. Around the same age I started exploring my genital area and got frustrated when it felt wrong and I couldn't fine the 'hole'. Now, bear in mind here I didn't know anything about the physical differences between boys and girls other than 'girls don't have a penis'. How my tiny brain knew about the 'hole' and where it was supposed to be, I have no idea. The only explanation I have would be some kind of body 'map' that was wrong for my birth sex.
I also linked my digit ratio in another thread, which is very extreme. This is ratio is sexually dimorphic and I have an extreme fermale ratio rather than the one I should have for my birth sex. A lot of trans women have a similar ratio, indicating it's very likely there is indeed a physical/hormonal component to being trans.

I'm sceptical of it because I can't feel anything like that. Since finding feminism I relate to women a lot more and can see that I am one, but I always hated the idea, and definitely never 'felt like a woman' or felt comfortable with girls growing up.

Did you ever want to be a boy? Did the desire to be a boy burn inside you and intrude on your life to the point where sometimes you felt like you were going to die from the burning in your breast? I think that could be the difference that is missing. You don't sound 'trans' to me, you just sound mildly atypical of your birth sex.
Personally, I think there has got to be a 'body' component to being trans. Possibly a combination of genes and prenatal androgen exposure; and this in turn affects the mind.