This isn't really the place for "help me improve my dps questions" but some quick pointers.

You are way over the hit cap. You should be aiming for 267 hit rating 8% hit as horde, so you are currently almost 200 hit rating over the target while still using enchants that give hit rating (this results in a lot of wasted ilevel). Your expertise is very low, you have zero expertise from gear, only the 6 from Vo3W. You should aim for 26 expertise.

You gem for ap/sta and for arp. You should aim for using str gems and use str/sta to meet the meta gem requirement. At your current ap you should not gem for ArP either. You might even see a dmg increase by getting som expertise gems, although the effect of them might be minimal as you are not going to hit the soft cap anyway.