In before Aethien comes in frothing at the mouth screeching SMITE SPEC FTW!!!
You will make it to 80 this time. I'm fully confident that at the very least, we are cool enough for you to stick with your priest, just to hang out with us.
I don't know when the last time you tried a priest is, but since the end of BC when spell damage and healing became the same thing, it became a LOT easier to level a priest in any old spec you want. This is good news, because if your stumbling block before was not enjoying shadow (which, weird, but I've already adjusted to your being weird from that bit about Draenei being cool), you may find a Disc or Holy playstyle to be different enough to capture your interest. I leveled my last priest Disc (Shadow for the first one) and it was great fun because of its versatility. You can heal battlegrounds, heal instances, and solo quest in all the same gear and spec. This is something I miss when leveling alts whose efficient questing spec is melee and I need a second set of gear for healing.
If you do choose not to level as Shadow, you will use the so-called Smite spec. People define that in different ways but really all it means is you've got 2/2 Searing Light and the Smite glyph. You can do this as Disc or as Holy, depending on which style you prefer. My preference while leveling was to do
this first, then straight up the Disc tree. I liked the extra bit of mana and stronger shields Disc offered while leveling. But Holy is great fun too. You will be pleasantly surprised by how much damage you can do with this spec while still being a kickass healer.
Your first 3 points go into Spirit Tap no matter what. Mix Eagle, Owl, and Whale gear until you get to Outland (with less emphasis on Stamina if you're not doing PVP). After that Spellpower - Int - Regen (MP5 for Disc, Spirit for Holy) and Stamina. You'll need the standard amount of Hit if you're doing anything offensively, and as far as Haste and Crit go, you kind of need to pick one until you get to a high enough level of gear to have meaningful amounts of both.
Hope that helps to get you started.
Give it some time, it's not like the pally where you just kick butt from day 1, but once you get rolling it's a whole different thing. I find my priest to be by far the most offensively capable healer I have, and that kind of balance is great fun to play.