You could run WWS, which parses the combat log of everyone running it.
I've found with addons like Recount or SWStats, your damage is accurate, but others damage is not totally accurate on your screen.
A lot of the addons have a sync option, which helps a lot. Even with sync, my Recount is usually slightly different from the raids WWS report.

WWS is free, and it will show the actual damage you deal with all your toons.
If that's too much of a bother, get the addon Recount, have it run for each of your toons and enable the sync options.