Your post caught my attention, as I have a 6 y.o. child diagnosed with Asperger's Syndrome and I am well familiar with the warning signals. The behaviors you describe are very familiar and concerning. We experienced those same behaviors and more at that age. I would definitely seek the help of a professional, but please beware of pediatricians! Unfortunately, a lot of pediatricians are not trained to identify autism, especially where they use a basic developmental screening test that does not necessarily raise flags for autism. I was told by three different pediatricians that my child's developmental delays and weird behaviors were 'normal' and not of concern. I believe they may have been eluded by my son's great eye contact and outgoing nature. I'm sure you understand that the earlier you catch it the better your chances for successful intervention. Since your son is under 3 you will qualify for services provided by the state. Please, seek the help of a professional who has extensive experience with autism specifically!! And hang in there, things are going to be challenging and exhausting (I'm sure they already are), but you are asking the right questions now and that's going to help you so much.
Good luck with your journey! My heart goes out to you...
Thank you for taking the time to write about your child. The first thing you need to do is to discuss your concerns with your child's pediatrician. Some of what you describe occurs in some children with autism, but some also occur in typical children with they are young (e.g., babbling). It will be important to make a list of all of the concerning behaviors your child has, and have examples of times he does this, so that the pediatrician gets a good feel for the extent of the issues. For example, saying that "he never sits still" may be overlooked, while saying, "During a typical afternoon, from 2-5 PM, he sits still for approximately 5 minutes; the rest of the time he is running in circles, and jumping on furniture, etc.", may be taken a bit more seriously.
I would also ask your pediatircian if there is anyone in your area who specializes in the assessment of young children with autism. It certainly would not hurt to get the opinion of someone with expertise in this area, as early intervention is crucial for successful intervention.
Best of luck!