Breastfeeding and sleeping

For some reason, as of today, my baby will only sleep if she's laying with me. Shes 12 days old and this is my first. I'm not sure if she's starting to cluster feed... she was fine all through the day, then slept for 30 minutes after I fed her for 35 minutes (normally she'll sleep for 2.5 hours.) She was up for a while so I fed her when she started crying and ate for about 8 minutes (tried to wait until I knew she was hungry.) She fell asleep when I was holding her for about 30 minutes. After over 2 hours of being awake, she dozed off and on for 30 minutes and woke up hungry and chewing her hands, so I put her on the boob with us both laying down on her side.. she ate for 10 minutes and passed out hard. I had to pee so I put her in her little sleeper in the bed (where she normally loves) and instantly woke up screaming and still tries to eat her hands. This is the first time she's doing this...