Help!

My son is on this insane up and down schedule with feedings and sleep! It’s seems like it is impossible to get him to stay on a schedule... my husband works 5pm to 5am I try to get my LO asleep for 8:30 9ish. Some nights he is passing out around 6:30 others he wants to be awake to midnight! He wakes up at 5am every morning and normally goes right back to sleep after eating. I try to give him solids before bed every night I mean no ones perfect so we aim as close to 7:30 8ish as possible so it has time to digest a little before going right to be he normally falls right back asleep after waking up at 5am and will sleep till around 8:30 9ish then he will take a short like 45 minute nap and hour or so later cause he is tierd again then any where from 1 to 5 he wants to sleep again... I have no clue how to get his schedule more strict as he kinda freaks out about everything when he is tierd he screams till I rock him to sleep... he is 5 months old.. any advise would be awesome!