Why can't I remember?

I'm turning 15 in a couple weeks, and from January to late May, I always get really prone to anxiety/panic attacks because I was sexually abused from that timeline for months. I was sexually abused when I was 9 on the bus, and always get extremely anxious when I sit near the area it occurred. I have to miss out on class when they talk about rape, or anything sex-related because of these attacks. I'm beyond jumpy. At night my dreams consist of rape. I always feel like I'm forgetting if he truly touched me or not. That's the most important part, but I can't REMEMBER it. And for some reason when people probe too deep into it, I blackout and have a screaming/crying fit. I can tell you his face, I can tell you the seat number, and even what I was wearing when it first happened, but why can't I remember the most important thing? Is this what PTSD is? It's weird that I keep getting triggered by rape stories even though I don't think I was raped. I know it was sexual abuse because it went on for a long time and I remember hearing his words and me trying to escape. I'm just missing the most important piece.