Well, your talents aren't too bad. On trash we tend to not do so great on the damage meters though. Check it on bosses only, that's where our DoTs shine.
I would drop Imp CoA if I were you. It's a personal choice though. The way CoA works all the damage is backloaded, therefore, so is the bonus. Unless CoA is always running it's full course, it's almost a waste of talents. On bosses in instances is the only place it is really really useful IMO.
Emp. Corr is not really useful until after 40 when you start seeing a lot more +spell dam gear available. You don't have any, so until you do, that is also pretty much wasted talents.
Picking up Nightfall would definately help your damage, especially on bosses. If you DoT, Tap and Drain, while Draining you should get Nightfall procs, Instant SBs will definately add to your DPS. Maxing out Fel Concentration will help your soloing, but since your more interested in doing more damage in Instances, you may want to keep your points in Imp CoA though. In a couple more levels when you pick up Siphon Life, that will add a little more damage for you.
As for BGs, there's a lot of twinks in the 20-29 bracket, they're pretty hard to contend with, it gets better in the 30-39 bracket. Just stick it out until then, and things start getting better as you get more spells.