Sanchez, you just described Amelia perfectly - except she sometimes wakes for a night feed too. As the others have said, they sleep in 40-50 minutes cycles and it can be hard for them to resettle themselves to continue sleeping. The last two mornings A has slept for two sleep cycles, but apart from that she has spent the last two months only sleeping for 45 minutes at a time. As she gets older she will start to have less naps for a longer time.

Violet sounds like she is doing fine, if she was hungry she would be grizzling for more food and she certainly wouldn't be sleeping for 12 hours overnight.