If you think your numbers were fine on the target dummy and your gm was wrong just sim it and show him.
Simcraft isn't limited to just raid scenario dps. You can choose target dummy, disable all but your own buffs, and you have 4 different skill levels to choose from as well.
Actually, if anything, the target dummy is the closest you're ever going to get to see how well you perform your rotation/priority without the outside of effects of raid mechanics hindering you.
Heck, I'll run it for ya.
Edit for results
The stand in fire skill(lowest) -43k
So, going by that seems that you know your rotation well and your performing well for the gear you're in.
There is one thing to note though, those numbers are of an average 7 min fight. I don't know how long you attacked the dummy in game, but if it's substantially shorter then that, your in game number is abit inflated, being that, the shorter the length you attack the dummy the larger percentage of time under cds, which leads to higher average numbers. Though, not sure on this, I don't recall ferals being an overly reliant cd spec.
Also, it is simcraft, which doesn't always have priorities done well for every spec. However, still a good tool for measuring.
Another interesting thing to note is the difference between performing almost flawlessly to making mistakes often in your rotation/priority. It's not overly significant, which lends to the argument that knowing the fights and their mechanics and being able to keep up with that rotation while all that is going on is far more important. Which is the greatest of things gained from beating the hell out of the dummies, muscle memory.
Edited by Brugavino on 2/11/2013 10:11 AM PST