My 13 month old isn't walking yet. Isn't that really late?

Doubt it. I like to see a kid get themself to sitting by 9 m, pull to stand/cruise by a year and walk independently by 15m. If premi, i adjust my expectations accordingly. (1 month premi gets an extra month to do it) Review this with your doc. .
No. As long as your child is otherwise developing normally, this can occur. Your child should be able to pull them self to stand, walk with assistance, and cruise.