2 week old not filling up after breastfeeding and after formula. this usually happens at night. she becomes very agitated, crying but still moves her head to the side and opens her mouth as if she needs to drink. please help!

Check volumes: By 2 weeks, your breasts should be producing enough milk to satisfy the baby's needs. When your milk lets down at feeding, the first portion will be watery/thin, then progressively more fatty. Make sure the baby is on each breast through this whole cycle. Do not feed formula prior to/instead of breastfeeding, Regular stimulation of your breast via nursing will help you produce more milk.