I think it is very possible to block out trans memories, blocking memories is a common coping mechanism so I don't see why not.
But to you specifically, having no dysphoria or trans memories before puberty does not make you less trans, it just means you have a different experience, if that's what you're worried about. It's different for everyone. Some kids just aren't very aware of their bodies at all, especially if they have no sexual interest. So if you were already allowed to be like you wanted and not being forced into girly stuff I think it makes perfect sense that it can go more or less unnoticed for a time.
Myself though, I've carried those memories with me the whole way, what I did instead was keep telling myself I must just be confused or that it was normal to question your genitals, and things like that. That way I managed to stave it off most of the time.
I still remember very specifically from when I was 6, how - when I learned about the differences in male and female anatomy - I looked at my dick(my clit) and wondered why it was so small.
I was also already quite sexual while growing up, in a male way, which I was ashamed of, especially after the horrible scolding after someone found out what I was doing. That brought even more fear in me of ever telling anyone I felt like a boy.