4 month old won't sleep longer than 2/3 hours at a time during night

Any advice on getting my 4 month old to sleep longer than 2-3 hour stretches at night?

I have him on a pretty consistent feeding schedule during the day, 6oz every 3 hours and then around 2-3 oz before bedtime around 6-6:30pm. Usually in his crib by 7:30. His bedtime routine is a bath and aquaphor every night at the same time, and then he eats. I've been trying to transition out of his sleep sack, his