sleep apnea, or?

Hello, I am a 30 year old male who is 60 pounds overweight, however I do exercise for 30 minutes per day at a target heart rate of 150-160.  I have an ex smoking habit of about 12 yrs, 1 pack per day. My cholesterol is 153 and triglycerides are normal.

For about 6+ months I've been experiencing a constant very heavy, tight feeling in my chest that does not get worse with exercise.   It feels sometimes like it keeps me from getting a deep breath easily.  Sometimes I just feel breathless at rest.
I also have had symptoms of chronic lightheadedness and nausea, and feeling like I may faint (but my blood pressure is normal during these episodes).  These symptoms have become quite debilitating and disabling.

Sometimes i may wake up at night feeling like I'm having trouble breathing, or rather, a trouble sense of breathlessness,  but I never hear wheezing; I have even rarely awoken with severe sinus tachycardia of 160+, which was non-sustained, once I caught my breath.

I saw a doctor who had got me a chest xray, echocardiogram, and a regular stress test.  These, and my thyroid/liver, etc. were normal.

But, I have seen a new doctor recently and he has noticed from his new labs, and my old records that my hemoglobin is consistently high-normal for the past 3 years, (i believe he said it was 16.7...I forget if that was right).

He thinks this is a sign of oxygen deprivation at night and thinks I have severe sleep apnea.
Would you agree that these lab results and other signs point to severe apnea?
Are there other considerations to make as well, given the troubling chest symptoms I have?  The new chest Xray and EKG were normal, just the hemoglobin a bit high as usual.  (i live at an elevation of 800 feet and don't smoke anymore).

I will be having a sleep study soon, but I wanted to just see if this seems as cut and dry to you?
And importantly, are these other considerations to make given my symptoms?
Thank you.

[Cleveland Clinic]

It sounds likely to be either obstructive sleep apnea or obesity hypo ventilation syndrome. The former is more common and likely here, and may be causing, by decreasing the oxygen tension in the blood, an increase in your hemoglobin. You need a polysomnogram to document any apnea events. It is important to know this as there are well established cures to this problem, and untreated this issue can double your risk of cardiovascular morbidity or mortality.