The Chicken/Egg Continuum

My DD has no regular sleep pattern. At the age of 22 months, she sometimes sleeps for 10 hours at night. She sometimes sleeps a few hours, gets up for a few hours, sleeps a few hours, get up for a few hours, etc. Sometimes she's up early (today it was 4:30am, two days ago it was 3:30am) and sometimes she sleeps late (yesterday it was after 10am). I've gone through every theory. She's teething. She's getting sick, she's hungry, she's thirsty, she's hot, she's cold. She's a light sleeper, and wakes when I move. She's having bad dreams. Perhaps all of this is true at one time or another. Now I've forgotten the tie-in to the title of this blog. My brain, which works better with a consistent sleep pattern, is fuzzy, light-headed, drained, unable to hold a thought. We can't plan anything with certainty. When I suggest that late-morning is best as DD sleeps in, she'll be up very early, and we're sleeping by late morning. When I say that early will probably be fine, the opposite occurs. Is she waking cuz she's hungry, and therefore nursing a lot? Or is she nursing a lot because she's waking? Or is she going to have a lifetime of short, intense sleep sessions divided by short, wakeful times? She had no nap yesterday, and still woke many times to nurse and was awake for good after 8 hours. There went my theory (from Night Time Parenting by Dr. W. Sears) that she is simply getting too much sleep in a 24-hour period. Or perhaps that is the case but we need to be more consistent with an earlier, shorter daytime nap? But how do I get into that pattern when my brain is so tired and shot I can't imagine going a few more hours without sleep? On that note, DD is falling asleep, time to crash with her if I am to survive this day!