CowPimp is doing a good job answering your questions so far, but I gotta wonder, why do you do both flat barbell bench press and flat dumbbell bench press on the same day? Don't you think maybe you are over doing it? More certainly does not mean better. In fact, overtraining could very well be the problem here. My chest routine usually looks like this:
- Flat bench press
- Dumbbell bench press
- Dumbbell flies
(2-3 sets each)
And CowPimp is right, don't do leg and back together on the same day. It's good that you're even doing leg and back workouts, but just don't do them on the same day, it's too much. Try to break down your full body routine to four separate days (I find this is what works best for me). My training split looks like this:
Legs, Abs
Back
Chest, Shoulders, Triceps
Biceps, Forearms
Some people don't like to do back day the day immediately following leg day, because a lot of lifts use the same muscles -- but I have found it to be fine for me, since I don't deadlift heavy on leg day, nor do I do hyperextensions until back day. It's really a matter of opinion and what you feel works best for yourself.