Can I tell you something with 10 years professional experience?
She is lying - 90% probability
She's telling the truth - 10%
Her story doesnt check out properly mate..or atleast by what you have posted up here.
My advice is for you to lay the issue low for a while... then after sometime, as Specific delicate question as to what colour dress she was wearing.. what was the Show on the TV .. what sort of a Date of the week it was..
and by any fucking chance she answers all those.. then she's lying
Do know that almost all rape victims remember nothing but the actual scene or rather than incident.. not how it happened, not when it happened .. no background details
Just a little heads up mate..