False starts at bedtime

LO is about to be 4 months and I can’t seem to figure out a schedule.

I follow sleepy cues during the day and don’t really aim for specific wake windows, just go with the flow.

He has been waking up around 9a and we’ve (husband and I) been doing bedtime between 7-8p. He doesn’t sleep long for naps during the day, only 30min-1hr max. Sometimes he wakes up literally screaming with no known cause and it takes him a minute to calm down and go back to sleep, but usually just goes back to sleep.

When we put him down for bed, he wakes up within an hour. We have a solid bedtime routine with bath, sleep sack, rocking in a chair. Etc. all the things. He eats shortly after his bath, so I know he’s not hungry.

Then, for his final trick, he’s up every two hours for the rest of the night.

We’ve gotten some longer stretches here and there and the 4 month sleep regression I believe has passed. He can put himself back to sleep at night for the most part if he wakes up and he’s not hungry. I try to keep him busy during the day with tummy time, books, etc. FWIW I don’t think he’s teething.

I just don’t know what the answer is as far as getting some sort of consistency, a better start to bedtime, less nighttime wake-ups, etc.

Any advice? Suggestions? Help?