Ours has always slept under at night and in naps, only just under on a good day but always under. E.g. should be napping 2-3 hours a day and we get anything from 30mins up to 1hr 30 on a very good day.
Should be 12+ hours at night and we get 10 and a half up to 11 and a half max.
He just just 8 hours last night after a late bedtime and refusing to go back to sleep. He just sleeps way less than he's supposed to and can't help worrying about his development but honestly my life is about his sleep. It drives me mad.