Low Frost DPS in MoP, what am I doing wrong?

Frost 492 ilvl, currently doing normal HoF/ToES/MSV. My dps is significantly lower than other mages and dd with the same ilvl. I’m following the guides (at least it seems to me) - rotation, talents, caps, gems, glyphs, etc. I don’t understand what the problem is. Occasionally I catch up when I get lucky with a bunch of procs in a row, but it’s very unstable. Maybe someone could take a look at my logs/stats or watch some gameplay and tell what I’m doing wrong?