When should my 9-month-old see a doctor next?

12 months. The next well visit after the 9 month visit is at 12 months.
12 mo. If child is up to date on all vaccines and has no other medical issues, 12mo is usual next recommended visit. (Usual checkups if no other concerns & with exceptions: birth, 1,2,4,6,9,12,15,18, 19-23mo, 2-3yr, 4-6yr, 7-10yr, 11-12yr, 13-15yr, 16-18yr)
At age 12 months. Your baby's next routine visit should be at the age of 12 months. Bring your child's shot card to all visits.