Hey, friend, I definitely can relate to this, our parents genuinely seemed to try, to put forth effort, and definitely "weren't as bad as they could be", but I'd like you to consider a few things:
Things that may not seem so bad now as an adult, can be devasting to a child, especially a very young child. Being yelled at may not seem so bad, especially if you're comparing it to others' traumas, but being yelled at can be truly frightening to a child. If it frightened you, caused you go to into fight or flight and dissociate, then it was sever enough. Especially if it was happening a lot.
It doesn't have to just be from your parents. Teachers, grandparents, or other adults that could be seen as "primary caregivers" can also cause disruptions to having secure attachments.
Bullying, frequent illness, witnessing (domestic) violence or other things that may have been frightening/difficult for a child to process without help can all be forms of trauma.
Trauma is often less about the event itself and more about the fallout. If you didn't have support as a child especially after a difficult event that can not only cause the long lasting effects of trauma, but make them worse.
There is a good chance that you genuinely don't remember it all. (Please don't go looking for those memories.) That is the point of the system, to compartmentalize those memories so that you don't remember things.
Some folks are simply more prone to dissociation as a coping mechanism and this can absolutely affect system development and structure.
As we've grown, and learned to communicate with one another, we've come to learn that a lot of our trauma was more than just our parents, and was also the church and school environment.
It's easy to down play trauma, in many ways this is a means of protection for the system, but it can also cause feelings of invalidation for the system as a whole or specific alters. Even just allowing alters a place to vent their emotions or journal about their experiences can be helpful in combating those feelings of invalidation.
It's okay to be afraid of that or to be uncertain of your own trauma and experiences, but it's also okay to accept them at face value, it's okay if symptoms or memories or traumas or those things don't make sense right now.
