my son's sleeping routine is never the same

My 8.5 month old always goes to bed at the same time every night but his waking up in the morning and through the night changes all the time, sometimes he can wake twice through the night but occasionally he sleeps right through, or only wakes the once, what on earth am I doing on the days before he sleeps all night, I need to take note, I'm desperate to have at least a few full nights sleep 😴 does your little one wake different amounts each night?