See the problem is that you have 3.5k spirit, alot has changed since WOTLK and spirit is even more important now.
While leveling, your spirit will suck.. at 90 in 478 raiding gear I have 9k spirit. (Not even gemmed full spirit) On my monk which I currently main while raiding I have about 12-13k full buffed.
To fix your situation right now I would recommend getting all the spirit gear you can find and make sure everything is reforged to spirit. Then haste or mastery. There is no point in getting a haste threshold (3043) until you are 90 because the percentages scale.
When you actully are healing in a dungeon group and your members don't want to wait on you the best thing you can do is time your innervates. When you reach about 80 or 70% mana, pop innervate. Don't use innervate if you are about to end combat, try to save it for when you are mid fight or just starting a fight. The reason being is if you pop it when combat ends and then reach full mana before the next combat starts, you are essentially wasting that passive regen.
Make sure you have lifebloom up on the tank at all time, use regrowth on clearcasting procs and try to fill in with nourish. Nourish is a very meh spell right now, but at low mana levels its the best you can do. Only rejuv people who are taking active damage (tank, couple dps) Dont spam rejuv on everyone.. Make sure to use Swiftmend on CD and use Iron bark as a tank CD. I would also reccomend using Nature's swiftness (if you havent already) becasue that is about the only kind of burst healing you have outside of tree form right now.
Lastly, use Incarnation: Tree of life, and just spam lifebloom on everyone in the group and use your instant regrowth on clearcasting proc.s For the most part you will gain mana while doing this since all your spell costs are free from clearcasting.
I hope this helps.
EDIT: you can always ask the group to let you drink too lol. You might jsut ahve bad luck though, I have 2k spirit on the priest im leveling, i always have mana problems but I deal with it and just keep going, it also kinda irks me when they say "wait for healer to get mana" because I'm the type of person that jst wants to go as fast as possible. xD
Another tip is to get some of these from the Klaxxi if you have accessed them Restorative Amber
. You can only use it out of combat so it acts like food, but will fill your mana from 0 to full in less then 10 seconds.
Here is a macro I use for it:
/cancelaura Restorative Amber
/use Restorative Amber
Edited by krazyito65, 10 December 2012 - 10:21 PM.