There are areas that always have veins , the problem with being level 14 is that some of the better places have loads of mobs , its rocky areas and places like mines that you need to find , the dead scar has quite a few spawns in it but the mobs there will limit just how far along it you can get , the best bet at your level is to hunt down copper in the easier level places and remember where they are , i found by doing a large twisting circle around all the rocky areas i was able to get many stacks of copper ore , its memory of where you found them that will help you find more , not sure of any real great places though as the veins seem spread out around the cliffs .
if you were NE or Draenei there is one perfect place for copper ore in and around the stillpine ? hold , i can get about 4 or 5 stacks easily in an hour there
There is an addon i understand that will remember where you find veins , not sure exactly what it is called or just how good it is but i guess someone will let you know about that , i have never used it so cannot help you with the name.