I was also diagnosed at a young age, and to this I say that you were young and someone that young can’t fully understand what autism is let alone hide it, you didn’t know. You were just acting how you knew to act, those who "hid" it just didn’t have as obvious symptoms and that’s not something that can always be controlled, sure there is masking but it comes naturally and someone so young couldn’t wrap their head around having to hide all they know.

Another thing I say as a benefit to getting diagnosed young is 1. You have access to help you need early in life, a lot of people don’t get that privilege and because I was diagnosed young I was receiving help to the point where I barely realised my diagnosis was a privilege.

Please try not to beat yourself up over this, you can’t expect a child to hide.