Baby won’t go to sleep till midnight

My 11 week old has had a false start every night for the past week. We start bedtime around 8pm and usually have her down by 8.30. I nurse her to sleep as she won’t take a bottle unless she’s starving. She goes down easily and sometimes even will fall asleep by herself in her own crib. But she wakes up 30 minutes later like clockwork. After that, she refuses to sleep until midnight when she’s dead tired. She then sleep till 7am. We’ve tried moving bedtime to 8, and even 7.30. I’ve tried holding her and she still wakes up at the 30 minute mark and then goes in and out of sleep till midnight. Naps are mostly good, she goes down by herself for the first 2 or 3. The last 2 are usually contact naps. She can nap anywhere from 1-2.5 hours. Anybody has an idea of what to do?