My son is turning 9 months old tomorrow, but is his height too short? hes 27in and weighs 20lbs is that a normal height or should i worry?

Height: Given the measurements you provided, your son is about the 5% for height. As a single measurement it is not very informative. It is important to know what your child's previous measurements were. Is he following the same growth curve or is he starting to fall off? These are questions that your pediatrician will be able to discuss with you on your next visit.