I do not have TOS. It was a diagnosis that was ruled out. However in my search and in my many doctor visits, in reading your details it appears to be TOS - it was thought that I had it because of the ulnar nerve pain I had as well as my hand getting very cold and turning blue when I used it. So, as you did, I did the research and read many articles related to it. I am fortunate to live in the Boston area and have acess to many top notch medical groups. One referreal lead me to a Vascular specialist at Massachusetts General Hospital. He has written many texts about TOS and is in the process of writting a new text right now. He performed the usual exam on me with some of the tests turning my hand cold and blue. As a result he ordered a Cat Scan. The Cat Scan was an experimental scan that he has created with his team that is specific for looking for TOS. Although I had some usual syptoms my scan was negative and it was determined that I don't suffer from TOS.
Writing this post to advise as others have to seek out a vascular specialist that focuses on TOS or has experience enough with TOS to know how to look for it and exam you for it. I am not a physician, but rather a very experienced patient that has done extensive reading to try to find out what I have. I have also had many many appointments across many diciplines in the last few months trying to find an answer for my arm, elbow and hand pain. I have, in recent weeks been diagnosed with CRPS Type 2 - for quite some time my sypmtoms have walked the line of TOS. I spent a long while on many waiting lists and would like to see other wait less and get answers sooner.
Good luck - run a search for vascular doctors in your area, then when you call to make an appointment - don't be afraid to ask questions - ask if they focus on TOS - be bold, ask questions and own that conversation. If you are in the Boston area - I would highly suggest contacting Mass General's Vascular department. They were great, they did an extensive eval and even did all of the leg work with insurance to make sure the scans were covered. Although I was not diagnosed with TOS, that team was helpful and offered other specialists names to contact for pain help.
Have a good night.