I've thought of dropping the machine flys. I usually stall off the chest I find.
My body weight is 55kgs, I'm only benching 40 atm (started at 20 ).
My triceps is usually Two arms extension, Skullcrushes, standing barbell extensions, seated push down machine, overhead extension with a rope, pressdowns with a rope. A little unorthodox but I've made decent progress with this routine.
Well even though you said not to suggest eating more, gaining weight will definitely be the easiest option. Being 55kg you're primed to grow and grow fast.
Moving away from a program with a lot of isolation work and back to a simple compound program (ie starting strength), or if you want to do a split - this one from hato (whirlpool forums):
Monday
BB Squats 3x8
Stiff legged Deadlift 3x8
Single leg press 3x8
Calf raise 3x15
Wednesday
BB Bench Press 3x8
DB Incline Bench press 3x8
Standing Military Press 3x8
Close Grip Bench Press 3x8
Friday
Deadlift 3x8
Chin ups 3x8
Bent over BB row 3x8
EZ bar Curls 3x8
Eat a crapload more and try and get your weight up to 65-70kg - don't worry too much about fat gain, get some good weight & muscle on you first and then drop a bit of fat off in 12-18 months time.
There is only so much you can gain in strength without growing your body. And gaining weight/size/muscle is a whole lot easier than training to gain strength at the same weight.