Sleep Help

My 15 week old has only slept through the night a few times. His new schedule is nap around 7:30-8 pm wake up to have a bottle then back down around 9:30 or so (my husband walks him in his stroller to put him to sleep).. from then on he wakes up around 12:30, 2:30, 4:30, 7:00 to nurse and then he’s up for the day. 😭

I am so exhausted. I’m about to go back to work in a few weeks. Any advice on how to change up his schedule?

Would switching to formula help him sleep longer you think? I’m too tired to keep doing this.