Hi there!
A couple of things - 9 is really too late for a kiddo to be heading to bed. My son has sensory issues and got so overwhelmed and over-tired if he went past 7:30. So we started quiet down time at 7 to prep him for bed - dimmed lights, final meal all cuddled up, soft music if needed. Babies do need a lot of sleep and if he's dropping his morning nap then going to bed earlier is a good way to compensate (plus it gives you some time for yourself in the evenings). If it continues or gets worse I'd suggest getting him in for a behavorial appt. My son started doing the exact same thing and it got so bad I had to spend hours getting him to sleep only to wake up over and over and spend an hour sometimes to get him back to sleep. His sensory issues have been diagnosed and he sleeps so well now, even still takes a nap at age 4.
Also remember that every child is different (my second NEVER had sleep issues!). I hope things work out!