I think Cook is going to be worth it, and you have a really nice RB core, but overall depth and and Weakness at WR will be an issue.
I'm only in my 2nd year of a dynasty league as well, but here are some thoughts for whatever they are worth:
If Abdullah can string together a few nice starts, he might be a good piece to include in a larger package from some WR talent.
This might sound crazy, but I might try letting the league know that Gurley could be available for the right price, and see what kind of offers you get. You don't need to take them, but it's worth seeing.
Guys like K. Allen and Jarvis Landry are often undervalued, and might be targets. Dez owners might also be ready to move on, and he can still give you a few WR2 years if the price is right.
Realistically, you are going to need your youth to pan out, but in addition to their stats, pay attention to their roles on their teams and how they are getting their points. I personally don't like boom or bust players, and if you have a young TD dependent WR that gets hot, it might be a good chance to sell.