In reply to Mike Hewitt:
Hey pal,
I've never seen you climb, so I just wanna say that the following are guesses only.
Steep climbing, both indoors and out requires completely different technique toolbox than slabs. Drop knees, flags and outside edging (LOTS of this) are the most indispensable techniques in the arsenal of an overhanging climber.
Excellent starting point: look at ALL the similar videos
People say that slabs require a lot of technique, I agree, however I find when steep climbing is truly at your limit, technique to be crucial, as soon as you step on the wall your power is decreasing and you need to be precise and efficient in every moment, when it is truly hard.
I imagine that if you shy away from overhangs you might be a bit apprehensive about getting on them or taking safe falls (on bolts, or on bomber backep up gear with a good belayer). Falling indoors and trying challenging things will eventually make you more comfortable dancing on roofs.
Breathing and moving at a good pace is also crucial on roofs...speeding up through the tricky bits and then getting something back at the resting jug that follows.
Finally, a good way to look at indoor walls is just as training ground that will enable you to do the routes that you truly want to do. Doing lots of steep leads indoor can certainly not hurt you when you're pressed with an overhang outdoors.
Good luck and enjoy!