Running out of Spec QueryFollow

You can expect to heal most non-heroic instances perfectly fine as a feral-specced healer. This is assuming you have decent gear to support healing, which it sounds like you do. Healing some of the easier heroics is possible as feral but you need to have a group that far outgears the instance.

I would say with 750 +healing and being feral you would be fine with any non-heroic with the exception of Arcatraz, Shadow Labs, and possibly Steamvaults. If you got to about +1000 you would be fine with any non-heroic.

If you are seriously interested in healing I would suggest going resto or, if the lack of additional soloing utility bothers you, try out a hybrid resto/balance such as dreamstate: http://www.wowhead.com/?talent=0xcrzicshuZZxVcxcq . With either a resto build or a dreamstate build like the one above you can expect to heal any non-heroic and much easier than healing as feral. Also when you hit roughly 1000 +heal you can start healing heroics and Kara if your interested in raiding.

When I was balance spec'd, pre resto, I had around 1100 healing in my off set and the best instance I could heal was heroic ramps up until Naz/Varz then I would need some help from another off healer.

If you want to heal as said before by Treehands, going with a dreamstate(restokin) build is a good way to heal it'll make it so you're not totally nerfed on doing damage. I'm full resto and killing things in dailies sucks for me now. But also going full resto means you become a way more efficient healer. I used to go oom when I would offspec heal and now going oom is almost non-existance. My mana bar now can last me much longer than the six minute cooldown innervate has so I pretty much have gotten to the point where I'm almost at infinite mana.

I will say this about off spec healing though, it's so much nicer not being pulled out of tree form if you need to toss out a big heal from Healing Touch. I had to get around this by doing the ole NS/Regrowth/SM route.