Roofies dull the senses and stuff. It could be that your body has decided you can't deal with the trauma and has repressed it. It could also be that you've accepted it happened. It could be that sex doesn't matter to you and you don't feel it was a violation.
I'd say, if you have the means, go to a therapist or a psychologist to get ahead of the game if it turns out to just be a delayed reaction. If not, journal writing, what happened, how you feel about it now, why you think that is and how you expected to react and why that is.
Another tool to see how you really feel is to free draw a shape, don't think about it, just whatever you instinctively feel the need to draw. Maybe you'll colour it in, maybe you won't. But the shape and the colour and the density of the colour will tell you everything you need to know about your current state of mind.