As much as I agree with you about how your mastery is iffy, with affliction having a good mastery its dps is still horrible. Destro by far is the top dps spec for a lock right now, followed by demo, then affliction (according to EJ). So by all means, don't feel bad. I played affliction throughout WoTLK, and it's pretty much not viable anymore (at least to min/maxers like myself). So as much as I love affliction, I'm going to bring my best dps to raid.
I'm sure in time things will balance out and all three specs will be similar dps. Just not sure how long that's gonna take