I think your spoiler is closer to an ISF than some people think.
It does resemble mine, but hard to tell from the picture. The F-sport one is definately more agressive than the IS F and partially cuts out around the logo on the back of the car. The F-Sport also has a more pronounced lip than the ISF.
If I had to make a judgement call from those pictures, I would say yes...what you have is pretty close.
IS F Spoiler (borrowed picture)
F-Sport Spoiler
Digger08