As you stated using the aggro bar isnt really the best way to determine how much dps you are doing. At i110 with nexus im doing about 340-350 dpish on turn 8, so if you can constantly hit around 300+ in the SCoB (excluding t7 if u kite) than imo you should be fine. Like Isomy stated, no matter how you look at it, our numbers aren't really big lol. If in doubt just do the usual "DPS Priority" check.

Buffs up? go to dots. Dots up? go to dps move. If neither are up? reapply. In bards case, always have straight shot crit buff up. But dont just spam straight shot for its buff. I like to reapply straight shot when it has about 1-3 seconds left unless it got a free crit proc from heavy shot. Keep up windbite and venom bite. again dont constantly reapply them. Wait till they are near the end of their timer. I usually weave in bloodletter with both dots because each dot least about 18 seconds and Bloodletter is a 15second recast timer. by the time bloodletter is up, you dots should be near the end of their duration. But if you get bloodletter free proc than just use bloodletter and reapply dots whenever there at 1-3 seconds left of duration. Use flaming arrow when available. People ignore blunt arrow and Repelling shot as OGCD but you should use these 2 skills as part of your rotation. But be careful with Blunt Arrow if the fight requires a silence rotation. Even if it just a little, little is better than none.

The rest is just how you use your buff skills like Blood For Blood, Raging Strikes, Internal Release and Hawkeye.