My CSA happened when I was about 4 or 5. A relative too. It was a long long time ago and attitudes and legal processes were a lot different back then, so I have no relevant advice for you on that.
However, what I can tell you is that after the medical exam, which was done forcibly to a very scared little girl without any discussion or warning by the family GP, my parent's decided not to go to the police, and to brush it under the carpet. They never spoke to me about it again and if I touched on the subject it was abruptly shut down by them. The GP said that I was so young, and the abuse was not actual rape so I'd forget. I didn't.
All I saw around me was angry parents and I internalised that and blamed myself for their anger because I didn't have the understanding or the language to discuss or process what had been done to me, they felt that by discussing it would impede the forgetting that the GP said would happen (didn't help that it was a repressed religious upbringing either so 'rude' stuff was never openly discussed). I blamed myself. As an adult I was able to discuss what happened and how I felt but as a child, with my parents, I couldn't and that was what did the damage to me, not the actual incidents themselves. I was a bit of a wreck as a teen and in my twenties and I attribute a large part to my early childhood experiences.
These days there are specialised resources and child therapists that help a child so much. Avail of these all you can. Even if she seems fine and cannot verbalise it, she still needs to process it, and it will help her heal quicker than I did.
I think you are doing wonderfully. I wish my mum had been like you when I was little.