10man should be fine get a couple items out of it and you'd be fine to start 25man. I wouldn't worry too much. your defense is fine and you have enough health to start going there, the place isn't incredibly difficult as long as you have a good group and know how to do each of the bosses.
enchant your bracers maybe, add a belt buckle with gem, and possibly a sword enchant. Start going and working on your gear from raiding, do sartharion as well and archavon for shots at more gear. Then post again if you have questions but atm until you do that tank thing and dive into it there's not much else people can tell you