Hey,
I'll try to help but, the information you gave is a bit lacking. A character armory would be much more helpful, however I understand if you do not want to disclose it. Regardless of that:
1.Talents
I'll assume you have the
standard spec, or some slight variation of it. Little reminder here to not forget your glyphs of
Arcane Blast,
Arcane Missiles, and
Molten Armor.
You might want to think of incorporating Incanter's Absorption, Magic Attunement and Magic Absorption to your spec once you get the hang of it and obtain better gear, but for now you can work with the standard cookie-cutter one.
2.Gems
You should be gemming
+23sp on red sockets,
12sp+10haste on yellow sockets, and
12sp+10spirit on blue sockets.
Some also prefer to gem +23 sp on items with poor socket bonuses (i.e +5 sp or less). While preferences may vary, you should always consult a spreadsheet or RAWR to give you a better, less subjective verdict.
3.Hit rating
You mentioned trying FFB and FB specs as well, but since the thread title is about your arcane dps, I'll stick to that.
The hard cap for spells is 17% hit.
You're very close to the soft hit cap. As Arcane, you reach your soft hit cap at
8%. This varies depending on how many points you put into
Arcane Focus and
Precision. Assuming 3/3 on both, you get
6% hit from talents. In raids you get another
3% from
Balance Druids/
Shadow Priests.
This leaves you with 17-9=8% hit to be obtained from gear.
While missing 1% hit might seem trivial, depending on your (mis)fortune, it can impact your dps greatly. A missed spell does no damage, and considering your gear level, that's ~2.1 seconds wasted per missed spell.
4.Enchants
A little 50 spellpower here, a little 30 spellpower there, in the end it adds up.
If gold is an issue, try to at least get the faction-specific enchants(i.e Kirin Tor, Sons of Hodir), and enchant those pieces of armor you do not plan on changing soon.
5.Rotation
Make sure you're doing the correct rotation!
Your default Arcane rotation should be 3 Arcane Blasts -> Arcane Missiles.
If,however, you do not get a Missile Barrage proc, do NOT cast Arcane Missiles. Keep casting AB until you get a proc.
Do not go with 4AB->AM rotation as your default, it will drain your mana while not granting you any additional dps.
When you obtain your 2 pieces of tier10, you will want to start incorporating the 4ab+am cycle to your rotation, but until then it's not worth it.
Do not clip your spells! Make sure you're letting all missiles fly and not clipping them. Try to steer clear of [nochanneling] macros, unless your latency is well below 100ms.
6.Gameplay
Sometimes this is just as important as doing your rotation right.
Position yourself well. Move as little as possible. Always be casting.
Arcane is the least forgiving spec of the 3 when it comes to this.
Interrupting casts or generally moving a lot is detrimental to your dps.
I'm sorry for the long reply, but since you can't tell what's wrong from your post, I just went over every potential setback you might be encountering that I could think of.
Hopefully you find something that applies to you and might help! :)