Hmm...your DDs been at daycare, and now you are home for the summer. Are you a teacher by any chance? I am, and I have the same issues, so maybe we can support each other? I just got done with teaching and am on summer break myself, and I have to try to get my lo back on EASY since she went off of it due to daycare. I also have problems with inconsistent morning wake-ups. More often than not, my DD wakes too early!
Anyway, my first question to you is...Is your DD waking up hungry at 3:00 or 4:00 AM? Are you breastfeeding or formula? It seems odd that she's sleeping through the night some nights then would be waking up to feed sometimes and not at others. Can you eliminate this feed?
Next question... what time do you want DD to wake-up?
Next thought is on days when she does sleep through the night, have you tried w2s to extend her 5:15 wake-up?
Mika