Sleep Regression at 14 months?

My DD has always been a good sleeper (don't be too jealous, my DS was a  nightmare sleeper and still is!).  She would go to bed pretty easily around 7:30 and then wake up somewhere around 7am.  She's been doing this since about 8 months old.  Over the past week or so, she has started to get up earlier and earlier, culminating in a 5:45am wake-up this morning.  

Her bedroom is pitch black with blackout curtains, so I don't think the light is bothering her.  She wakes up crying and is then cranky, so I'm pretty sure she's still tired.  She is transitioning from 2 naps to 1 nap, so that could be it, but I didn't think it would screw with her sleeping this much.  

We have tried putting her right back in her bed, rocking her for a bit and then putting her back down, letting her CIO, bringing her into our bed, putting her to bed later, putting her to bed earlier, and nothing has made an ounce of difference!!!  I'm really hoping this is just a phase, but I was wondering if anyone else is going through this and 1) has any ideas on how to make it better 2) can say they recently went through this and it just lasted a couple weeks or 3)  have no other ideas, but wants to commiserate with me.   

ETA:  The title should say 14 months.  Clearly I'm a little sleep deprived!