Autism, as you may know, has such a wide spectrum. The fact that you are socially withdrawn, could mean you have social anxiety. The fact that you need everything explained to you step by step could also be a learning disability, not necessarily Autism.
I highly recommend that you see a specialist. A clinical psychologist can thoroughly evaluate you. There is help out there, you just need to know how to access it. You could also start with your own family doctor to point you in the right direction.
I could give you examples of symptoms of Autism that I have experienced with my 15 year son, but he was diagnosed when he was a toddler. Though I know that there are adults who have been diagnosed with Aspergers, which is another form of Autism. It's just best to get a professional opinion. If your primary doctor doesn't take you seriously, then find someone else who will listen. Doctors don't know everything.
Take care of yourself & I hope you have family support!
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