The problem is not that there is a problem with your site. Its merely that the big boys realized that there will me money in that niche over the next 2 week-month and decided to get involved. Dont blame Google, you just got outplayed.
-Kobe Beef - 'My dinner gets more love than I do'
Well, as a guy who plays the niche faithfully, and has for 2+ years I can tell you that you're pretty close to right. Here's what actually happened though...
Twilight fans are some of the dumbest shits in the world, and they will do absolutely whatever someone tells them to do, so they are pure bank.
The problem isn't the big boys, though they're surely into it. The problem is EVERYONE is sniping this movie's release. Not just smalltime players, but people who actually know quite a bit about SEO, and they are all chasing the same dream with the same/similar tactics.
Don't give up OP. You took action, and maybe it won't pan out, but don't let it beat you up. If you keep pursuing things, something will come together for you.
It took me over 3 months to get good with my promotional methods for movies, and I've adapted them 20 times since starting. Stick with it!