Your starting to see the weaknesses that shaman's face in PvP in general. Granted we find more success in BG's and cluster fighting than 1v1 conflicts. I'll state some pro's and con's first, then how to apply yourself in which BG.
Shaman's (enh or elem) are blitz fighters and HIGH burst dmg class. Think of yourself more akin to a glass cannon tho. Your goal is to kill something faster than they can notice you. Easier said than done obviously. Because of this 1 dimentional tactic, your gearing for melee stats NEEDED to be MAXED. In some regards "twink" needs to be the norm for Enh shaman's, just to find moderate success.
Big downside to Enh is the fact that even though you "have" ranged attacks like LB, you might as well be throwing 9volt batteries at your target :P So basically all your dmg comes from melee, which means you have no flexibility for dps. Big disadvantage in a world full of CC's and distance controlers. Thus, you best plan of attack is to stay with your teams cluster and pound on targets that are already engaged with your teammates or don't notice you yet. Going in weapon drawn and charging (there's already a class that specializes in that..and we're not it) in screams "free honor" to your enemys. Think "rogue" like, just without stealth :p
Another factor is that regardless of spec, your enemy see's you as a potential "healer"...HELL even your teammates see you JUST as a healer (regardless of spec!). While the answer is "yes" that you "should" heal situationally, the fact remains that a shaman (especially a Enh shaman) doesn't have the MP pool to support full time healing and dmg. Course Enh gearing doesn't/shouldn't support caster stats to begin with. I bring this point up mostly because, since you CAN heal, and your enemy knows this...your public enemy #1! And you will be singled out and taken down FIRST! More so enforcing the fact that, stick with cluster to max your kill rate as well as your surviability! Being a lone wolf (pun intended) is unhealthy!
Now on to BG roles;
WSG- Due to the fact that we're one of the few classes at your lv bracket that has a method of enhancing movement AND carry a flag, this becomes a mainstay for WSG! While Ghost Wolf has some BIG advantages in flag runner, keep in mind some obvious disadvantages.
#1- Going back to my cluster fighter mentality I mentioned, if your moving faster than your support team can keep up, you can get singled out faster.
#2- Its purgable!
#3- Shapeshifted form doesn't make you immune to impairing abilities
#4- Takes time to apply (unless you NS it, which is something I typically don't like blowing on)
#5- Can't cast/heal while transformed.
Understanding your weakness, helps you focus coordinating your strengths with your teammates. A well cooridinated GW run can get a flag from A-B faster than anyone, especially in that bracket and can blitz win WSG in just a few mins!
Combining blitzing dmg, occational heals and quick flag runs makes shaman's deadly in WSG!
AB- While GWing to flag points cool, as I already mentioned...singling yourself away from your teams cluster is a really BAD idea. This being said, due to the nature of a shaman's abilities (totems specifically), where better at "defensive" support, IMPO. Take a point with a team, setup shop (in the form of totems), and guard it! Course, in my experiance "guarding" stuff in AB can be difficult since everyone seems to like to "defend" things by constantly running around the map :P But, as many vets can attest to proper GUARDING is a key aspect of victory in AB! We do this well, as long as we're not the only ones staying to guard a spot :P
We're strongest once we have a full 4 element layout down. Defending something allows us the time to setup. When blitzing a point, it will take a full 4 secs to get out our tools, more than enough time for a enemy to drop us, espeically if they singled us out..and they tend to do that alot as I mentioned.
Setup shop, keep a good defense squad with you, and GUARD! Spot heal and kill as needed.
Some last helpful tips
You can use Ghost Wolf Offensively too. Even @ 70, I tend to move around in GW form more often than not. Reason being is 2 fold;
#1- its obviously faster (DUH!)
#2- its A LOT less obvious to my enemy moving around in a semi-transparent compact-DOG shape, rather than a Tauren atop a War Kodo!
If I know that the class tends to get singled out, then why would I intentionally wear a BIG NEON SIGN telling my enemy where I am!?!
Since Shaman's don't have a real movement enhancing abilitiy to help get us into melee range faster to be a proper "blitz" dmger, we're relient on just our typical "walking" pace. Your enemy will see you coming a mile away typically, and gives them more than enough time to counter your forward advance. About the only thing we have to close the gap faster is GW.
I use a macro something like this;
/dismount
/cancelaura Ghost Wolf
/targetenemy [target=mouseover,nodead,harm]
/startattack [harm]
This allows me to stay in GW/mounted right up to the point when I'm in their face, then I can start pounding on them immediately!
IF by chance your a Tauren, make a macro something like this;
/castsequence reset=War Stomp [Target=player,modifier:shift] War Stomp, Lesser Healing Wave
/use [target=mouseover,help,nodead] Lesser Healing Wave
This allows for quick cover heals to your team, by simply mousing over their picture, or their character, OR if you hold down SHIFT, its your "OS" button, allowing you to do a AoE stun, and get off a (hopefully) uncontested Lesser Heal on yourself. You "could" do a normal healing wave, but considering that the War Stomp blows the Global CD, that means that you actually only have 2 secs "usable" stun time, not 3 like the tooltip states. So, that means you only have enough time to squeeze in a LHW (1.5sec cast), where as IF you used a normal HL, your enemy has 1 sec to interupt it. Giving someone like me 1 sec, thats more than enough time for me to earth shock a heal, since I already had 2 secs prior that it was being telegraphed!
Hope that helps