The phone you have is actually called the LG Optimus Q, why they call it the Zip in certain places is beyond me, because Zip, Q and Esteem are the same model of phone, but you'll have the best luck if you look up rooting information for the LG Optimus Q. Trust me, I literally just went through the same thing you did (I'm still setting up my phone.)
Okay pm and I will help you try to root your phone I know a way