it looks like you have a lot of overlap with your drivers. if you lack the accuracy to work lines with your discs consistently as you say, then it would greatly benefit you to simplify your drivers and work more on learning to work one disc, then move on from there.
The Surge, Flash, Nuke, and Northman all probably could fill the same spot in your bag. They are all considered 'stable distance drivers' for the most part. Their flight characteristics are all very similar. Pick your favorite - or in lieu of a fav, pick the surge, it's probably the best of that group - and stick with it for a while.
There is probably some overlap between the assassin and the roadrunner also. at your power range, both should be in the understable/turnover driver category. choose one and stick with it (i'd recommend the roadrunner)
you seem to be lacking a true overstable disc. consider adding a predator, firebird, xXx, or the like to your bag for big dependable hyzers in all wind conditions. the king has some natural high speed turn from what i've read, which could potentially bring about inconsistency for a headwind drive - it may still flip more than you want. hope this helps.
Ability is what you're capable of doing. Motivation determines what you do. Attitude determines how well you do it. -Lou Holtz -