I see no one has responded in half a year and as I just stumbled upon your post, I saw fit to write a short answer to your problems.
Prolonged shortness of breath (accompanied by other symptoms as for instance lightheadedness/dizziness and headaches) are sometimes caused by, as you stated, chronic hyperventilation. This means that you either inhale too deeply or inhale too frequently for a longer time. GERD is known to cause shortness of breath when acid reaches airways, but as I read your story I do not think GERD is the cause for your prolonged experiences with SOB.
Based on the relief you feel when taking supplements of which you believe they help, in combination with positive effects of exercise and the overall prolonged experience of symptoms, chronic hyperventilation does seem a reasonable explanation for what you're experiencing. This, as I read your story (no obvious signs of disease/malfunctions concerning heart or lungs) leads me to believe your problems are not physiological at base. It is known that anxiety and/or depression can influence breathing severely. These mental issues are not always obvious in daily life. Many people don't know they're going through such issues. Have you considered looking in this direction? If you keep experiencing the same symptoms in the same manner, it could be fruitful to consult a therapist.
Since it has been 6 months, may I ask how you're doing now? Have you noticed improvements? If so, how did you improve your situation?
Best regards and I hope this answer helps!
PS I am not a doctor. I have however read (way too many) studies concerning this specific issue.