Lvl 21 Conj here and i've noticed too a very low number of Conj drops during dungeons too

To become a better healer what i did was to go to a populated hunting ground [area where a lot of people do their leves] and try and keep everybody healed. Of course since you aren't on their teams, you'll have to display PC health bars constantly via the options but this creates an awareness within you to be constantly checking out a large number of health bars and to teach you the basic skill of move + heal.

Seems like such a simple idea but it really does help a lot and got me personally ready for the dungeon runs i then have done. Simply this is because my mind is now trained/ready for 10 - 15+ players which constantly need heals compared to a dungeon in which i only have to heal 1/2 people at a time.

Plus, you get a lot of "thank you"s while "training" there which always makes a healer feel good