Good morning, and welcome to JA.
It's important for you to know that it is both inappropriate and unethical to diagnose over the internet (and across the Atlantic Ocean!)... so I regret that providing a diagnosis isn't possible today.
However, that being said, it certainly sounds as though you've done your homework and have some valid questions to ask.
It is important to recognize that Autism falls along a spectrum - and that the behaviors range from mild to severe/profound, and can be different for every individual with autism. Add to this that there are a number of other disorders along this spectrum that might also qualify (Asperger's Disorder, Pervasive Developmental Disorder). Also, a number of non-Autistic disorders may, at certain times, present as autistic-like. These might include: Attention Deficit Hyperactivity Disorder (ADHD), Nonverbal Learning Disorder (NLD), Severe Speech/Language Disorder, Tic Disorder/Tourettes, some anxiety disorders (like Obsessive Compulsive Disorder (OCD)), Sensory Integration Disorder, etc.
The only way to really tease apart all of these variables is to work with a licensed mental health professional (LMHP) in your area. Here in the U.S., typically only Psychologists and Psychiatrists diagnose Autism - but I know of some other professionals (ranging from general physicians to social workers to speech/language pathologists) who may do so as well. It will be important to have someone with a working knowledge of both autism as well as development - because they will need to ask a lot of questions about your childhood. (This is not probing for deep dark secrets or anything - just so they understand your developmental trajectory - speech/language development, social skills, academics, sensory issues, etc.)
I believe that, even if you don't have an Autism Spectrum Disorder (ASD), it might be work your while to work with an LMHP to better understand some of the questions you have. Your questions are valid and warrant working with a professional who has appropriate background to help guide you to your next steps.
Thanks. I hope this was helpful!
* FEEDBACK ENCOURAGED. Please contact me prior to leaving negative feedback so that we can resolve the matter. I am eager to work with all JA clients to provide them with useful/helpful answers. Thanks again.