okay, i just looked at your workout and diet, and here's a few of my thoughts
1 - your diet is a little calorie deficient. serious mass (your weight gainer) is liquid calories, which do not count when counting base (maintenance) calories. i say this because 2 servings of serious mass will not maintain your size, even though it would hit 2.5k calories. if its 1.2k extra calories, then by all means you're doing it right.
2 - split up your serious mass. 1 scoop preworkout, and 1 scoop postworkout will hit the 1200 calorie mark, and will give you 2-3 extra reps per workout. postworkout, more than 30g of protein is a waste anyways, so this will work best for you, and provide you with the all important preworkout nutrition. it did for me at least - serious mass still is one of my favorite bulking shakes, and is part of my diet - post 44
http://anabolicminds.com/forum/training-forum/99607-gaining-mass-nutshell-2.html#post1568261
3 - if you're all out bulking, you need to stick with the exercises that allow you to use the most weight (barbell or smith), as isolation won't bulk you up much. a list is at the bottom of post 1 here :
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IMO you're really shorting yourself without consistent deadlifts/pullups, on back day, etc. also with the push/pull routine that has been suggested in other threads, you could do biceps on back day, and quite honestly, if you haven't done biceps after weighted chinups, you've never seen a bicep pump before. anyways, hope this helps you in some way.
also, i don't see any rear tricep work, which is around 1/4 of your arm mass. to target these, do tricep pulldowns with an underhand grip (yes it feels weird). again, good luck my brotha.