Bard DoT kills take some 3 to 7 minutes, depending on the level, and the instrument. That *is* a slightly long time for a kill. Most other classes kill faster. This is offset, however, by the fact that you have *zero* downtime, unless you feel like taking a break afk or something. It all balances out to approximately the same solo xp per hour.
One joy of being a bard is in your adaptability. If something is either going too slowly, costing you too many HP, or just no fun...adapt, improvise, overcome. Try a new song lineup. Try a new tactic. Try a new zone/mob lineup. You have a lot to experiment with.
You have a bright future. Find it.