K.:.
Why can't you get to bed before midnight? Is there any way you can get to bed any earlier?
It's most likely a phase. My DD has always been an early riser, and it doesn't matter what I do, that's how she is. She did go through getting up at 5, 5:30, and has now finally settled between 6 & 6:30. Have you tried a white noise machine, darkening the room, etc? What about an earlier bedtime & working towards dropping the nap? Maybe she's getting too much sleep. I would NOT put her to bed later, that never worked with my DD, she would actually wake up earlier.