I've been looking for a long time now and have found no hallow, except in my ice biome, which has some pink ice, but not low enough for crystals. I've also planted some hallow near my house.
I've been looking for a while now, and know that hallow spawns in a V or X shape, and I still have nothing. I've considered making my other world hardmode, but I'm not for using up more stone.
I need the crystals for the Phasesaber because my Night's a Edge is too slow, and not helping much, as I'm swinging very slow even with a legendary prefix and not going faster than my Pwnhammer, which has been more useable.
Talk to the dryad, since she tells you how much of your world is hallowed/corrupted. If she says something like 7% hallow, 20% corruption, you may be in a rather bad situation. Also, the V or X of hallow may have passed through too many non-hallowable blocks, such as snow or mud, and thus may not have hallowed enough blocks to spawn any shards. You may be screwed, sir.