This is for every concerned mother: Have your children tested! You have nothing to lose, and help for your child to gain. I'm an SLP and did Early Intervention for 2 years before quitting to raise my own kids. Federal law allows for family-based services to infants and toddlers 0-3, because helping these young ones makes a huge difference in outcome! Services should be free or with a minimal co-pay. It depends on your state. You should not need a referral from your MD. To get information on where to find services, try your school or doctor. Your childdoes not need to "be cooperative"- professionals know how to get the information that they need (Including lots of questions from you about his history).
Based on what you describe your son should qualify for services(10 or fewer words at 2 years), but it depends on your state. If he's on the edge of qualifying, they will likely monitor him at least. Have your son tested soon: first because services will change when he turns 3 (depends on your state laws), also because there can be a waiting list.
Your son may have a "typical" delay and could catch up without help (in which case help won't hurt, just be fun and prepare him for school!), or he might have difficulty with the incredibly complex task of speech (in which case, the sooner he gets help, the better!). He's learning and understanding more every day, and soon will realize he has ideas he can't convey to you.
Nothing that you mentioned would make me worry about autism. Also, learning signs won't hurt, and may help ease frustration and give him success at communicating-- it's a good place to start, but the very first step is to trust your instinct and find a good SLP! You're a great advocate for your son! Best of luck.