I'm confident your problem is overtraining, and I'm going to provide you with the same bit of radical advice that the "Master" himself provided me.
STOP TRAINING YOUR CHEST.
Yes. That's right. And I know 90% of you are dismissing this post based on that one comment, but bear with me here.
If you have been training your chest that heavily that often, I'm postive you have created a serious ammount of neural inhibition. NI is a defense mechinism created by the body that does not allow your muscles to fire at their full potential inorder to prevent injury.
So now, go to the mirror and do a test for me. Stand completely profile (sideways) and look at your back. If you can see the upper part of your back AT ALL during this pose, it is an indicator of Upper Crossed syndrome - which basically means that you have a HUGE imbalance between your chest and your back. Remember, you should be able to row exactly what you bench press - and more importantly, for every set of work you do for your chest and shoulders combined, you should be doing the same ammount for your back.
So now, to default on a more experienced coach than I am, Ian King gives a remedy for this:
For the next 6 weeks, do NOTHING for your chest and front deltoids but stretch them. Take weights, lie back on a bench in a fly position, and just go to sleep. You will need intense bouts of stretching, for no less than 5-10 minutes at a time at least 4 times a week to see the progress you need.
Also in these 6 weeks, strenthen your back. Spend a day doing nothing but horizontal pulls (rows...all grips) and a day doing nothing but lateral pulls (pull ups...all grips).
At the end of the 6 weeks - I promise - you will have added size to your circumferance, and your chest will have actually grown. The first week back during chest training, you will have lost some strength - but by the following week, it will have returned, and you will in fact be over your plateau.
Take this for what you will...but that is the answer you need...although I'm confident it is not what you are looking for.