M.L.
Hi there and welcome! I am saying this from experience - Don't let anyone tell you he's too young to worry or just wait and see because boys develop slower.
My son, now 5.5, was the same age when I realized my friends kids (same age) were pointing and responding to their name or seemed to know, if you said you were going somewhere, to walk towards the door, many other examples......anyway, my son didn't seem to understand any of this. At his 12 month check up this was brought up to the dr. he said, as others have said, this should be emerging in the next couple of months, comes see me in 8 weeks and we'll see if he's progressed........he didn't and we got a referral to the Illinois Early Childhood Program.
People looked at me like I was crazy or thought I was an idiot for talking about my son getting evaluated. We got his ears checked, hearing was fine.....next was an evaluation with speech therapists, OT, etc. Turned out, from their evaluation, that he qualified due to deficits. he started speech therapy and developmental therapy.
I won't get into every stage of his life, but will say - my son has on the fence diagnosis of ADHD and/or PDD-NOS (autism spectrum). however with the early intervention we were able to get him the most support as early as possible.
My son is going into Kindergarten this year and he has graduated out of speech therapy as he has met and exceeded his goals!!!!
Trust your motherly instincts and let peoples comments roll off your back - you are your childs best advocate. I am glad I didn't listen and take the 'wait and see' approach.