You are doing more than you need to relative to arm work.
If you gain overall body mass your arms will get bigger. Makes sense? It should. I have never seen a 250lb. man who lifts big poundages and has small pencil like arms. Are you with me on this?
If I were you, here is what I would do: Concentrate on the big movements: Squats, Deadlifts, Chins, Overhead Press, Dumbbell Bench Press. These type of movements. You know?
Keep the sets around 4 or 5. And the reps between 6 and 10.
You will get plenty of work on your Triceps with the pressing movements. You will also get enough bicep work by doing Chin-Ups! (Ever do a negative Chin? We will have to talk sometime).
And don't forget to eat plenty of good healthy, natural food. In three words: Always be full. And supplement with Grow Protein Powder! You will need about 175 grams per day..or so.
Oh, and get plenty of sleep, at least 8 hours a night.
4 months from now you will post a message about how you gained a solid inch on your arms...or somewhere around there..
Best Of Luck To You,