Hello, I am new here

My shadow priest had 1263 shadow damage and 76 hit (with all the 5 points on Shadow Focus).
My dps suck though, couldn't get it pass 530 looking at wws.
I read this thread and also talking to other shadow priests, I can't understand how some of the shadow priests here can output over 1k dps!! Hell, 800 would be a dream come true to me!
This was my standart rotation:
VT
SW;P
MB
VE (after giving the tank some time to build agroo)
SW

(only when my hp is above 50%)
MF (only if everything else is in CD or the dot weread off).
I have Dottimer (sp?) and "face melter" (where I have the above spell rotation set as my priority).
I also don't stand around "doing nothing" - I am always casting something if I don't have to move due to the fight.
I had oportunities to raid with other shadow priests and although they had less bonus shadow damage, they output a much higher dps.
So, after looking at the armory page of some priests from high end guilds, I noticed their gear is stacked with haste. Because of that I decided to swap some gems around and invest in some haste to see if it would make some difference.
Currently I am sitting at 1226 bonus shadow damage and 90 haste rating (or 5%). After many tries on Dr. Boom and looking at my wws, I can get to around 700 dps - what seems low compared to the reports I read in this thread and considering that in a raiding set I can't just stand dpsing all the time. Most of the fights require some moving, so I will lost some casting time.
After reading this thread I am going to resp to take one point from Shadow Power and max my Improved MB, besides that I don't see much else I can do. So, if any of you have suggestion/advices for me I would greatly appreciate it!!! Specially concerning how to maximize my dps output (of course without sacrificing mana regen to party members).