Been playing enhancement from the start of BC but at the moment I've been struggling to keep up with my raid on DPS. It's the start of a new tier so my gear is a little off. Any helpful suggestions and advice is very welcome.
Your gear seems to be fine, and the developer's even mentioned that this tier favors melee. I could see it as a scaling issue (which Enhancement is usually affected by a lot) but I see a lot of Enhancement shaman doing fine.
Enhancement is a very easy to learn hard to master specialization, as long as you've got your damage priority right, you should be fine. My best bet though, would probably be the alignment of cooldowns.
I play Elemental and have only recently got my Meta gem. I align all of my cooldowns (Potion, Gloves, Orc Racial, Stormlash, Spiritwalker's Grace) into an Ascendance macro which keeps me on top for quite awhile (higher than a few people with cape, actually), and I'm always on top during AoE phases. I'm probably the second, or third least geared damage player in my raid group but I'm still in the top few.
Maybe try and do something about your cooldowns, that might help. We're a very cooldown-oriented class.