I'm guessings you picked #1, which is an unenviable position in a big league this year I think; things are starting to look pretty thin by the #28 pick, whereas having two picks in the teens is nice.
You could definitely use help at RB, but you're not in bad shape if Pierre's health holds up. In a big league, the waiver wire should be scarce at this point, so I doubt there's much you can do now.
If one of your WRs has a big first 2-3 weeks but seems like a flash in the pan type (i.e. Stuckey last year), then I would try to move him for the best RB you can get (using the old "sell high, buy low" principle).
Other than that, just keep your eyes peeled for emerging guys, using your waiver priority carefully (can't afford to waste a pick in a big league), and check out matchups to try to get your best WR options in the lineup each week.
You're in decent shape, and one or two shrewd moves could give you a big edge this year. Good luck!