Here are just a few signs if a child may be autistic:
Child may avoid eye contact with you (majority of the time)
child doesn't like to snuggle or lay in you lap
child doesn't respond when you call his/her name.
Child may need loud stimulation like a lot of banging or screaming, more than typical.
Walked on toes when learning to walk
shaking of arms
Child tends to repeat things right after you've labeled the item.
Please keep in mind that this is just a few things and if your child only shows signs O. of them or two, then I wouldn't be too concerned.
One other thing, Does your child understand things? For example if you tell him/her that it is time to brush his/her teeth, will they go to the bathroom to brush? Or does the child need direction on everything?
My daughter is 19 months and she is hardly speaking at all. However, she seems to understand everything. So I wouldn't be too concerned, but you may just want to get your child screened and then you can will know for a fact. Because if there is a problem, hearing, autism, or something, then it is really is important to get help now. The sooner the better. I have a friend who had found out there son was autistic and when they finally did diagnose him he was 4. They ended up getting him detoxified when he was 6, and it did a lot of good, but since they waited so long to dignose him the outcome was maybe not as well as it could have maybe been if they did it when he was younger.