I entered heroic instances with 18k HP on my tank and worse gear than yours.

What I had cristal clear at the beginning was that one of my shamans had to be a dedicated healer and the dps ones needed enough DPS to down trash packs in 2 minutes and bosses in no more than 4 minutes because that was the time my healer ran oom while nonstop spamming lhw on the tank.

During the first week I just made myself a list of bosses to grind list. I farmed ONLY these bosses because they were easy and I could use their badges to buy better gear. Also these bosses were very easy and fast to reach in most of the cases.

1 ) Mamooth boss in Gundrak --> just interrupt hist transformation with earth shock
2 ) Snake boss in Gundrak --> Place your shamans on the stairs at the "arena" looking thing where the boss is. Tank the boss in the middle of the arena. Drop 3 x healing + 1 mana totems and 4 Fire elemental totems. remember to pop heroism. The fire elementals and the paladin consecration will keep the snakes away from your DPS and healer and will most probably give you the boss specific achievement the first time you do this boss in this way.
3 ) Prince Keleseth in UK --> Shadow resist aura. Run to him, drop healing totems and 4x magma totems. Then DPS the boss and ignore the ads.
4 ) Contructor and controller in UK --> Put the shamans on follow and run to the boss. Drop 4 x grounding totem and magma totems. Burn the caster first and then the melee. Keep grounding totems and magma totems as much as you can. Having the shamans near you will prevent the melee guy from charging at your healer.
5 ) Orc commander in Nexxus --> Just kill him. He is an easy miniboss and drops a badge
6 ) Culling of stratholme --> all the bosses are easy. Just ignore the timers and take your time. The first time I downed that instance it took me lots of time, but gor very good gear. In the zombies place just keep your magma totems up to prevent zombies disrupting your casting.


You will find that you can down some other bosses too, but these are a sure kill with your current tank and gear. In a couple of days you will have enough badges to buy yourself some better gear and down entire instances.