B.H.
He sounds like he may be a little behind but I wouldn't say a whole 6mos. behind.
They're best bet is the have a 12mo. check-up and tell the doctor exactly what he's doing or not doing.
My daughter was 2mos. premature and caught up by her first birthday. My nephew was 3 mos.+ premature and it took him til he was almost 2 to catch up at most things.At his first birthday party he couldn't sit up, or feed himself.He also has mild cerebal palsy. If he is behind and it's because of the colic or something he could totally catch up. If it's a permanant problem like cerebral palsy, down syndrome, etc... he may never catch up or it may take him longer. You would just have to have a doctor evaluate this.There's alot of babies with serious problems that go totally undetected. And there are alot of babies that don't look like they have cerebral palsy, down syndrome, etc....Sometimes they look absolutely normal.