you should divide you responsibility into two functions:PM and business requirement.as the PM manager,you should breakdown the project schedule in detail,as to your project plan,it's too simple to contain all the activities in a project,even some of phases are tailored.the second function you should focus on is the communication between the end users(department leaders) and technique engineers,as the bridge between those two roles.so you can escape your weakness in technology and utilize your strenth in the project.and therefore take a critical role in the project.your subordinates will not lookdown on you accordingly.if you can balance these two function,successfule gain the project you will,I promise.