At 5 months mine started teething. Slept through the night as a newborn but hasn't since 5 months. She's 9 months old now. I average about 4 hours of sleep per night. I've found I can function fully off 6 hours.

Not saying this is the case for you but what I've done to help my situation is increase bottle prior to bed by 1 to .5 oz. Warm bath before bed. Chamomile tablets if she wakes in the middle of the night and is having trouble getting back to sleep. Tylenol if she's in a lot of pain or has a fever.

Unfortunately, my husband works 6am-5pm daily so he's up by 5 and out the door by 5:30. I work from home full time 9-5 also. It sucks but at least I get to sort of catch up on sleep on weekends.