I have had very similar experiences and memories from the same age in my childhood come to light recently. They revolve around my biological father in the bathroom as well.
One memory I have he is getting out of the shower and I have to pee. He tells me to come in do it. When I start to pee he stops me and tells me I have to take off all my clothes to do it, just like him. He stands there naked and watches me. In this memory, I know what is coming next. He walks toward me and I look down at the floor and the memory stops. I have enough body memories to know what happened next.
The other memory I have is riding behind him on a bike in one of those child seats. My big toe dangled into the spokes of the back wheel and the toenail popped right off. So, he takes me home bleeding and crying. He sits me on the bathroom counter and doctors my toe. After he is done, he starts rubbing my legs and my body. He starts to take off my clothes. Again, this memory whites out at this point, but I know what happens next.
I always had the first part of these memories, asking my father to pee and the toe in the spokes. I just recently recovered the second and most damaging parts of these memories that highlight how abusive he was. I think my mind decided I was ready for it, and released it. My mind did not ask for a unanimous vote thought, because I didn't feel ready when they came. They floored me quite literally in the form of flashbacks and panic attacks. But, I guess my mind was right in some sense, because I am still here plugging along months later after these revelations.
I have always said that this work is terribly difficult. But, in the end, I am sadder yet stronger. I am more me by what I discover, but it is a tough road to walk down or to have learned that I walked down as a very young child. But, I am still here. I am plugging along. And so are you. Take that to heart at the very least.
"Great spirits have often encountered violent opposition from weak minds."