Inconsistent wake up times

I’ve been lucky that my daughter has been a good sleeper since she was 8 weeks old so maybe I’m being greedy but she has very inconsistent wake up times. One week she’s up every day at 5:30am, the next week she’s sleeping until 7:30am. Sometimes it’s like this day to day. She goes to bed at the same time every night. She knows how to put herself back to sleep but when she’s up at 5:30, the only thing that will console her is a bottle, even though I know she can go longer without it. Anyone else experiencing something similar?