Not enough milk?

My 5 week old seems to sleep and feed well in the day but stays wide awake and fusses a lot at night. He is usually satisfied from just breastfeeding during the day (sometimes he falls asleep right after sucking just one side) but at nights, breastfeeding alone doesn't seem to be enough. Night feeds include breastfeeding + expressed milk as top up + even formula as additional top up. He's also super fidgety at night. Is this normal?