Your son sounds just like mine! My son is also 27 months and not talking. He is learning new words almost daily, but doesn't use them regularly at all. He does communicate non-verbally. Early intervention has not been a great experience for us because he's only given 30 minutes with an SLP a month.
I am starting private speech therapy for him next week. It will be 3x a week. I'm hoping this helps!
Eleanor, mama to Maren (07.05.08) and Grant (10.20.10)