Thank you for your response. I hope the ENT can give more of an insight. In the meantime I had been in communication with some doctors who specialise in balance dysfunction and they think that this condition I have is somehow all linked to the Benign positional vertigo I had 2 years ago. Apparently because the BPV was lengthy (6 months) before being treated, my body has compensated by tightening inappropriately and excessively. I am told it is treatable but it takes time . On the one hand I am happy with this new information by my new doctors, disappointed that for over a year I was being told it's all anxiety. Thank you for your assistance.
If your jaw is pushed that far back, then you're likely to have a sleep-breathing problem, but maybe not severe enough to be called obstructive sleep apnea. You already probably sleep on your side or your stomach to compensate. Bending your head forward and back can definitely affect the size of your upper airway, especially the space behind your tongue. By definition, you won't be able to sleep effectively and will be prone to stress and anxiety issues.
Who you should see depends on what kind of problems years of have. Ideally you should pull the lower jaw forward, which will also pull the tongue forward. There are various orthodontists and oral surgeons that deal with these issue. The ENT can also give you an opinion from an upper airway perspective. Good luck.