So before you ask:

Yes, I'm patched fully.
Yes, I have Dragonborn and Dawnguard.
Yes, I've had dragons spawning all the time on other characters.
No, I did not have problems with the game around 1.3 when everyone else seemed to be having dragon issues.
Yes, I progressed the main quest to where I should be getting dragons.

That out of the way, this character is a level 15 Nord warrior.

I've created three other characters in the previous 2 weeks, all of which got random dragon encounters. Frequently.

This character.. poor Kaelia.. she's gotten a few word wall dragons, but doesn't have enough souls to unlock the rest of her shouts. Miiraak, luckily enough, hasn't come to jack the ones I have gotten, probably because of my lack of actually progressing anything in Dragonborn. I have, however, been attacked by cultists.

And 3 DB assassins.
And vampires.

But no dragons. And I am a sad, sad Nord.

I haven't seen any reports of this happening recently, yes, I did a search.

Ideas?

The only mods I have installed are the unofficial Skyrim, Dawnguard and Dragonborn patches, and I just installed those today. I've had the issue since creating the character early yesterday. And I have almost 15 hours of play on her. >.> Don't judge me!!

Halp?

I've seen posts suggesting this happens occasionally.

You could try the http://www.uesp.net/wiki/Skyrim:Console

getglobalvalue dragonsreturned

If it's 1 then dragon spawns are set normally.

If it's 0 try the command

set dragonsreturned to 1

You can manually spawn dragons via the console command

player.placeatme 000FEA9B

I use a mod that decreases the spawn rate, so there are likely mods that increase it.