Looking for some adviceFollow

This is my mage's armoury: http://eu.wowarmory.com/character-sheet.xml?r=Anachronos&n=Gilaine. I seem to be doing low dps in heriocs i:e around 1200 - 1400 dps and I don't know why. Was hoping you friendly people could look at my gear and help me out a bit. Is my gear, my spec or do I just suck? or all 3? lol

Heroics are not a good measure of dps, the trash are probably dead before you get a 2nd or 3rd cast off... Whats your dps on the bosses like?, at least they'll survive long enough for a LB to go off. :)

Your hit rating is a little on the low side as well, perhaps not for heroics, but for raiding it is, unless you have a boomkin or shadow priest in your group.

Do you raid at all, or do you just do heroics? Raiding in general you get a better idea of what your DPS is like. For one, you generally have more buffs, especially if you use flasks and food. Like Anobix and axy said, the bosses are up longer and you have more time to do DPS. This is particularly true of Fire and FFB mages. Arcane mages have a little bit more leeway on Heroic bosses, but on trash our DPS still sucks. Me for example, I do upwards of 5k DPS in raids, and 8k on mage friendly fights like the twins in ToC. In heroics on trash I tend to do about 2.5k DPS, which really irritates me. Granted that's with blizzard attacking 3 or more mobs at once. If there's just one or two targets I'll stick to the typical arcane rotation and usually do about 3.5 to 4k DPS.

And yeah, like Anobix said you need to change the mp5 and stamina gems and the leg enchant. Change your two blue gems to the SP and spirit gem. Spirit is much more important stat to stack than stamina, as we get extra crit with the Molten Armor glyph. Crit is much more important than health.