Nothing screams overt sexual abuse, like communal bathing for same sex isn’t necessarily a bad thing. Though the duct taping your boobs, for example, that’s not really normal either. Other things, the burning when you peed, that could have been a unitary tract infection. If you still get that now, do see a doctor. As for humping the bear, and the two experiences with other kids, lots of kids will imitate what they see ion tv or movies, or they often will explore these things just out of curiosity, so nothing too strange there.

What stuck out to me the most was the knife for cutting yourself. Self harm is often a product of an extremely invalidating environment. So I’m curious rather than exploring sexual abuse, if you feel abused but can’t put a finger on it, have you looked into what emotional invalidation is? Because all those experiences could feel normal or even comforting to a child who’s emotionally validated and feels safe to set boundaries and object to things they don’t like. But a child that is repeatedly emotionally invalidated, and feels they can’t object or set boundaries, those experiences could feel uncomfortable if not unsafe and scary.