Is it normal a 4.5 month old wakes every 3.5-4 hours (twice a night) wanting to eat? she falls asleep on own with a paci and once out is good.

Common if: If you feed them as the last thing before going down it becomes part of their back to sleep ritual. No kid or adult sleeps more than 4 hours without stirring & changing sleep levels. Infants often wake. If you separate the last feed from sleep by at least half an hour this may stop. Remove the paci, it falls out & she will wake demanding you put it back.