After years suffering with PTSD with sleep apnea without anything being in my STR records for fear of ridicule. How can I get service connection?
Service connection of a disability requires that the veteran claimant provide some basis for the claim. You tell me that there is nothing in your STR about PTSD or OSA and that makes your claim more challenging.
However, many of us who didn't avail ourselves of medical care while we were active duty will find that within the first year we're out we have all kinds of evidence generated at VA exams, private care doctors and so on. If you have sought health care in the first year after your exit from active duty, that is seen as a solid connection to your active service.
The more of this kind of documentation you have the better. If you're past the first year after discharge, your task becomes more difficult as time passes. If you've waited a decade to seek compensation for service connected conditions and you have zero evidence of why VA should do that, your challenge becomes near impossible.
I know of mental health claims for PTSD based on sexual assault that was never reported and those claims were won after clinical psychologists agreed that symptoms were appropriate for an event having happened but those are few and far between.
If you believe that you have enough after service evidence of treatment to support your claim you should proceed to file with what you've got. If and when you're denied you can retain a veterans law attorney to help you appeal and you won't have any out of pocket expenses. Good luck.