Contact Early Intervention for a free evaluation at your own house (or at your daughter's day care provider if that's where she is during the day.)
Everyone is correct -- expressive langauge delay is only one of the key issues for Austism Spectrum Disorders (ASD). However, if your gut is telling you something is wrong, then have the evaluation done. Trust your instincts.
-- 16 months is definitely NOT too early for a Developmental Pediatric Specialist to be able to diagnose ASD. In addition, a speech therapist would, absolutely, see and treat your daughter for a developmental delay at 16 months (if the treatment is necessary.) There are hundreds of issues that can be addressed by a SLP even before the first word is spoken. Finally, therapists will have an "accurate picture" of whether or not your child is meeting the developmental milestones at ANY age.
-- "Had it and Lost it" (ability to speak) is NOT the hallmark of ASD! It occurs in some cases -- but not all.
-- The "Give her time to grow" or "Let's wait and see what happens" is old-school thinking. The earlier you intervene with the approrpriate services and support for a child with developmental delays, the better. Unfortunately, too many "regular" Pediatricians are still waiting too long and taking valuable time away from a child who needed intervention.
From my experience, if you are not seeing social or interaction issues (does she point at things to show you? Does she look to your face to see if you are looking at her? etc.) you probably don't have to worry about ASD. But...why not have the evaluation? Best Wishes.
(Do I really have 2 posts on this topic? How did that happen?)