My tank had 17k HP when I started doing heroics. His gear was very similar to yours.

My DPs shamans still have lvl 65 green gear on some of their items. Just don't want to waste gold knowing that in two days I will have enough rep to get them much better gear.

The only toons that I cared to gear was my tank and my healer.

Go and make gundrak (normal) for the good tanking ring the last boss drops. The mamooth boss drps a nice mace for your caster toons. Just farm the mamooth boss until he drops all the maces... it's 4 resets per hour and you can reach him in about 5 minutes on normal difficulty... including the kill.

What you will need to do is force overhealing at the beginning until you get better gear. My healer still in a LHW spam machine... yet I have to see my tank die while he has still some mana.

Your shaman toons have very similar gear as mines, I could say even better because mines don't have the imba spell damage mace.
Basically, if you set a good healing macro you can do heroics with this group.

Some bosses you will be unable to down, but others will be easy.

This is what I can do with very similar gear to yours but with pala tank.

UK --> cleared. The last boss is a bit tricky. Keep your shamans close enough to each other, so they can top themselves with a single chain heal.
HoL --> first two bosses only. Ionar is impossible for now. You can do the first two bosses specific achievements, they are very easy.
HoS --> Krystallys only and you need to time heals properly. Perhaps you could do also maiden of grief since you have considerably more spell damage than me and I can get her to near 100 - 75k before wipe happens.
Gundrak --> cleared. Eck the Ferocious is more luck than anything else. If he enrages early it's a wipe no matter what. use nature res totems on eck and the colossus.
UP --> first two bosses. You cannot pass the 3rd boss with this gear, so don't try it for now.
Naxx10 trash --> abomination wing and undead is doable pretty easy... too bad it's only for the lols
Naxx25 trash --> abomination wing doable with lots of healing and patience. Undead wing only some mobs.
DTK --> cannot pass the first packs of mobs that do these shadow circles without wiping alot, so I don't do this instance for now.
Strat --> have not tried this one yet.

These are my toons, note how similar is our gear. all the improvements over your current gear are from heroic boss drops... the bosses I can kill and that are stated above. Some other are auction house items, or reputation/quest rewards.

Tank --> http://eu.wowarmory.com/character-sh...er&n=Loladinus
Healer --> http://eu.wowarmory.com/character-sh...usher&n=Tuljin
Good geared DPS --> http://eu.wowarmory.com/character-sh...usher&n=Buljin
Crap geared DPs 1 --> http://eu.wowarmory.com/character-sh...usher&n=Ruljin
Crap geared DPS 2 --> http://eu.wowarmory.com/character-sh...usher&n=Nuljin

In short... YES, you can do heroics