I've been training for a while, made some good progress size wise but I'm having a bit of trouble getting my body symmetrical.

My left bicep is lagging slightly behind my right and my upper right pec is not as defined as my left.

I've tried dabbling with extra reps for the underdeveloped muscles as well as adding extra sets where I only use the underdeveloped side. I've also avoided using the bar and switched in dumbells for all of my presses.

I haven't really had a great deal of luck with any method. Any advice would be appreciated.