did you go to the same PT/rehab therapists the whole time or did you move up to ones with more advanced training?

Most average PT places & rehab tend to implement a cookie cutter approach to therapy - same thing for all.
Doesn't really work for those w/TOS as we can have blood flow issues and /or nerve issues. Blood flow & nerves both affect how our muscles respond. We need to have skilled & individual PT plans with adjustments to the plan when needed.

A good one should be able to check your top rib/mobilize it if needed.

I don't know how much/often you are lifting / working out but overbuilding the neck muscles can be a factor with TOS. Crowds the areas- muscle begin to squeeze or press on the vascular system and/or nerves.

You may have some trigger points or sticky tissues causing some of your problems.
See Sharon Butler's website for more info on the sticky fascia & gentle stretching techniques - www.selfcare4rsi.com

Most of us don't do very well with resistance bands or free weights.
Generally after the symptoms & pain are reduced - then those things can be slowly introduced. But some are not able to get the pain reduced at all.
I caution you to be very careful with any strengthening for now , at least until your symptoms are greatly reduced.

What would you say your average pain level is per day?
none to 10 highest